<?xml version="1.0" encoding="ISO-8859-1"?><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<front>
<journal-meta>
<journal-id>1870-3542</journal-id>
<journal-title><![CDATA[Revista mexicana de física E]]></journal-title>
<abbrev-journal-title><![CDATA[Rev. mex. fís. E]]></abbrev-journal-title>
<issn>1870-3542</issn>
<publisher>
<publisher-name><![CDATA[Sociedad Mexicana de Física]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S1870-35422010000100009</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[Critical strings and analyticity of the &#950; function analyticity]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Martínez-y-Romero]]></surname>
<given-names><![CDATA[R.P.]]></given-names>
</name>
<xref ref-type="aff" rid="A01"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Rangel Orduña]]></surname>
<given-names><![CDATA[Macbeth Baruch]]></given-names>
</name>
<xref ref-type="aff" rid="A02"/>
</contrib>
</contrib-group>
<aff id="A01">
<institution><![CDATA[,Universidad Nacional Autónoma de México Facultad de Ciencias ]]></institution>
<addr-line><![CDATA[México D.F.]]></addr-line>
</aff>
<aff id="A02">
<institution><![CDATA[,Universidad Nacional Autónoma de México Facultad de Ciencias ]]></institution>
<addr-line><![CDATA[México D.F.]]></addr-line>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>06</month>
<year>2010</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>06</month>
<year>2010</year>
</pub-date>
<volume>56</volume>
<numero>1</numero>
<fpage>75</fpage>
<lpage>82</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S1870-35422010000100009&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S1870-35422010000100009&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S1870-35422010000100009&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[In this paper we study a simple analytic continuation of the Riemann &#950;, function, using Bernoulli numbers and an analytic continuation of the &#915; function in the complex plane. We use our results to study the critical condition in bosonic string theory. The approach is simple and gives the student an alternative point of view of the subject. We also show that the mathematical basis needed to understand the critical condition is based on well known properties of the Dirichlet series and the theory of entire functions, and is within reach of the average graduate student.]]></p></abstract>
<abstract abstract-type="short" xml:lang="es"><p><![CDATA[En este trabajo estudiamos una continuación analítica simple de la función &#950; de Riemann, usando los números de Bernoulli y una continuación analítica de la función &#915; e n el plano complejo. Utilizamos nuestros resultados para estudiar la condición crítica en teoría bosonica de cuerdas. El desarrollo es simple y da al estudiante un punto de vista alternativo del tema. También demostramos que la base matemática necesaria para entender la condición crítica está basada en las características bien conocidas de la serie de Dirichlet y de la teoría de funciones enteras, lo cual está al alcance de un estudiante de posgrado.]]></p></abstract>
<kwd-group>
<kwd lng="en"><![CDATA[Mathematical techniques in atomic physics]]></kwd>
<kwd lng="en"><![CDATA[group theory]]></kwd>
<kwd lng="es"><![CDATA[Métodos matemáticos en física atómica]]></kwd>
<kwd lng="es"><![CDATA[teoría de grupos]]></kwd>
</kwd-group>
</article-meta>
</front><body><![CDATA[ <p align="justify"><font face="verdana" size="4">Ense&ntilde;anza</font></p>     <p align="center"><font face="verdana" size="2">&nbsp;</font></p>     <p align="center"><font face="verdana" size="4"><b>Critical strings and analyticity of the &#950; function analyticity</b></font></p>     <p align="center"><font face="verdana" size="2">&nbsp;</font></p>     <p align="center"><font face="verdana" size="2"><b>R.P. Mart&iacute;nez&#150;y&#150;Romero,<sup>a </sup>Macbeth Baruch Rangel Ordu&ntilde;a<sup>b</sup></b></font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><i>&ordf; Facultad de Ciencias, Universidad Nacional Aut&oacute;noma de M&eacute;xico, Apartado Postal 50&#150;542, M&eacute;xico 04510 D.F., e&#150;mail: </i><a href="mailto:rmr@hp.fciencias.unam.mx">rmr@hp.fciencias.unam.mx</a></font></p>     <p align="justify"><font face="verdana" size="2"><i><sup>b</sup> Facultad de Ciencias, Universidad Nacional Aut&oacute;noma de M&eacute;xico, Apartado Postal 50&#150;542, M&eacute;xico 04510 D.F., e&#150;mail: </i><a href="mailto:macbeth.rangel@gmail.com">macbeth.rangel@gmail.com</a></font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2">Recibido el 11 de agosto de 2009    ]]></body>
<body><![CDATA[<br>   Aceptado el 10 de febrero de 2010</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>Abstract</b></font></p>     <p align="justify"><font face="verdana" size="2">In this paper we study a simple analytic continuation of the Riemann &#950;, function, using Bernoulli numbers and an analytic continuation of the &#915; function in the complex plane. We use our results to study the critical condition in bosonic string theory. The approach is simple and gives the student an alternative point of view of the subject. We also show that the mathematical basis needed to understand the critical condition is based on well known properties of the Dirichlet series and the theory of entire functions, and is within reach of the average graduate student.</font></p>     <p align="justify"><font face="verdana" size="2"><b>Keywords:</b> Mathematical techniques in atomic physics; group theory.</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>Resumen</b></font></p>     <p align="justify"><font face="verdana" size="2">En este trabajo estudiamos una continuaci&oacute;n anal&iacute;tica simple de la funci&oacute;n &#950; de Riemann, usando los n&uacute;meros de Bernoulli y una continuaci&oacute;n anal&iacute;tica de la funci&oacute;n &#915; e n el plano complejo. Utilizamos nuestros resultados para estudiar la condici&oacute;n cr&iacute;tica en teor&iacute;a bosonica de cuerdas. El desarrollo es simple y da al estudiante un punto de vista alternativo del tema. Tambi&eacute;n demostramos que la base matem&aacute;tica necesaria para entender la condici&oacute;n cr&iacute;tica est&aacute; basada en las caracter&iacute;sticas bien conocidas de la serie de Dirichlet y de la teor&iacute;a de funciones enteras, lo cual est&aacute; al alcance de un estudiante de posgrado.</font></p>     <p align="justify"><font face="verdana" size="2"><b>Descriptores:</b> M&eacute;todos matem&aacute;ticos en f&iacute;sica at&oacute;mica; teor&iacute;a de grupos.</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     ]]></body>
<body><![CDATA[<p align="justify"><font face="verdana" size="2">PACS: 31.15.&#150;p; 31.15.Hz</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><a href="/pdf/rmfe/v56n1/v56n1a9.pdf" target="_blank">DESCARGAR ART&Iacute;CULO EN FORMATO PDF</a></font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>Acknowledgments</b></font></p>      <p align="justify"><font face="verdana" size="2">This work has been partially supported by a PAPIIT&#150;UNAM (grant IN108309&#150;3). We acknowledge with thanks the help of Dr. L. Pati&ntilde;o.</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>References</b></font></p>     <!-- ref --><p align="justify"><font face="verdana" size="2">1. Kline, Morris, 307, November. <i>Euler and Infinite Series</i>. <b>56 </b>(1983) (5). <a href="http://links.jstor.org/sici?sici=0025-570X" target="_blank">http://links.jstor.org/sici?sici=0025&#150;570X</a>.</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8453493&pid=S1870-3542201000010000900001&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p align="justify"><font face="verdana" size="2">2. Grattan&#150;Guinness, Ivor. <i>The development of the foundations of mathematical analysis from Euler to Riemann. </i>(MIT Press (1970)). ISBN 0&#150;262&#150;07034&#150;0.</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8453494&pid=S1870-3542201000010000900002&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p align="justify"><font face="verdana" size="2">3. M.B. Green, J.H. Schwarz, and E. Witten, <i>Superstring Theory, Volume 1 </i>(Cambridge University Press,1987).</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8453495&pid=S1870-3542201000010000900003&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p align="justify"><font face="verdana" size="2">4. J. Polchinski, <i>Superstring Theory, Volume 1</i> (Cambridge University Press,2000).</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8453496&pid=S1870-3542201000010000900004&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p align="justify"><font face="verdana" size="2">5. C.V. Johnson, <i>D&#150;Branes</i> (Cambridge University Press,2003).</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8453497&pid=S1870-3542201000010000900005&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p align="justify"><font face="verdana" size="2">6. B. Zwiebach, <i>A First Course in String Theory</i>, (Cambridge University Press, 2004).</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8453498&pid=S1870-3542201000010000900006&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p align="justify"><font face="verdana" size="2">7. K. Becker, M. Becker, and J.H. Schwartz, <i>String Theory and M&#150;Theory, a Modern Introduction</i>, (Cambridge University Press, 2007).</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8453499&pid=S1870-3542201000010000900007&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p align="justify"><font face="verdana" size="2">8. L.V. Ahlfors, <i>Complex Analisis</i> (McGraw&#150;Hill, 1979).</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8453500&pid=S1870-3542201000010000900008&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p align="justify"><font face="verdana" size="2">9. George Arfken, <i>Mathematical Methods for Physicist</i>, (Cambridge University Press, 1985).</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8453501&pid=S1870-3542201000010000900009&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p align="justify"><font face="verdana" size="2">10. J.E. Marsden and M.J. Hoffman, <i>An&aacute;lisis B&aacute;sico de Variable Compleja</i>, (Trillas, 1996).</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8453502&pid=S1870-3542201000010000900010&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p align="justify"><font face="verdana" size="2">11. M. Abramowitz and I.A. Stegun, <i>Handbook of Mathematical Functions: with Formulas, Graphs, and Mathematical Tables, Ninth Printing</i>, (Dover, 1970).</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8453503&pid=S1870-3542201000010000900011&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p align="justify"><font face="verdana" size="2">12. C.G. Callan, D. Friedan, and A.A. Tseytlin, <i>Nucl. Phys. B</i> <b>262 </b>(1985) 593 </font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8453504&pid=S1870-3542201000010000900012&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p align="justify"><font face="verdana" size="2">C.G. Callan, C.R. Nappi, and S.A. Yost, <i>Nucl. Phys. B </i><b>288 </b>(1987) 525.</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8453505&pid=S1870-3542201000010000900013&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p align="justify"><font face="verdana" size="2">13. M.B. Rangel Ordu&ntilde;a <i>Under graduate physics thesis</i> (Facultad de Ciencias, UNAM, august 2009).</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8453506&pid=S1870-3542201000010000900014&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --> ]]></body><back>
<ref-list>
<ref id="B1">
<label>1</label><nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Kline]]></surname>
<given-names><![CDATA[Morris]]></given-names>
</name>
</person-group>
<source><![CDATA[Euler and Infinite Series]]></source>
<year>1983</year>
<volume>56</volume>
<numero>5</numero>
<issue>5</issue>
</nlm-citation>
</ref>
<ref id="B2">
<label>2</label><nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Grattan-Guinness]]></surname>
<given-names><![CDATA[Ivor]]></given-names>
</name>
</person-group>
<source><![CDATA[The development of the foundations of mathematical analysis from Euler to Riemann]]></source>
<year>1970</year>
<publisher-name><![CDATA[MIT Press]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B3">
<label>3</label><nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Green]]></surname>
<given-names><![CDATA[M.B.]]></given-names>
</name>
<name>
<surname><![CDATA[Schwarz]]></surname>
<given-names><![CDATA[J.H.]]></given-names>
</name>
<name>
<surname><![CDATA[Witten]]></surname>
<given-names><![CDATA[E.]]></given-names>
</name>
</person-group>
<source><![CDATA[Superstring Theory]]></source>
<year>1987</year>
<volume>1</volume>
<publisher-name><![CDATA[Cambridge University Press]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B4">
<label>4</label><nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Polchinski]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
</person-group>
<source><![CDATA[Superstring Theory]]></source>
<year>2000</year>
<volume>1</volume>
<publisher-name><![CDATA[Cambridge University Press]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B5">
<label>5</label><nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Johnson]]></surname>
<given-names><![CDATA[C.V.]]></given-names>
</name>
</person-group>
<source><![CDATA[D-Branes]]></source>
<year>2003</year>
<publisher-name><![CDATA[Cambridge University Press]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B6">
<label>6</label><nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Zwiebach]]></surname>
<given-names><![CDATA[B.]]></given-names>
</name>
</person-group>
<source><![CDATA[A First Course in String Theory]]></source>
<year>2004</year>
<publisher-name><![CDATA[Cambridge University Press]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B7">
<label>7</label><nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Becker]]></surname>
<given-names><![CDATA[K.]]></given-names>
</name>
<name>
<surname><![CDATA[Becker]]></surname>
<given-names><![CDATA[M.]]></given-names>
</name>
<name>
<surname><![CDATA[Schwartz]]></surname>
<given-names><![CDATA[J.H.]]></given-names>
</name>
</person-group>
<source><![CDATA[String Theory and M-Theory, a Modern Introduction]]></source>
<year>2007</year>
<publisher-name><![CDATA[Cambridge University Press]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B8">
<label>8</label><nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Ahlfors]]></surname>
<given-names><![CDATA[L.V.]]></given-names>
</name>
</person-group>
<source><![CDATA[Complex Analisis]]></source>
<year>1979</year>
<publisher-name><![CDATA[McGraw-Hill]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B9">
<label>9</label><nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Arfken]]></surname>
<given-names><![CDATA[George]]></given-names>
</name>
</person-group>
<source><![CDATA[Mathematical Methods for Physicist]]></source>
<year>1985</year>
<publisher-name><![CDATA[Cambridge University Press]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B10">
<label>10</label><nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Marsden]]></surname>
<given-names><![CDATA[J.E.]]></given-names>
</name>
<name>
<surname><![CDATA[Hoffman]]></surname>
<given-names><![CDATA[M.J.]]></given-names>
</name>
</person-group>
<source><![CDATA[Análisis Básico de Variable Compleja]]></source>
<year>1996</year>
<publisher-name><![CDATA[Trillas]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B11">
<label>11</label><nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Abramowitz]]></surname>
<given-names><![CDATA[M.]]></given-names>
</name>
<name>
<surname><![CDATA[Stegun]]></surname>
<given-names><![CDATA[I.A.]]></given-names>
</name>
</person-group>
<source><![CDATA[Handbook of Mathematical Functions: with Formulas, Graphs, and Mathematical Tables, Ninth Printing]]></source>
<year>1970</year>
<publisher-loc><![CDATA[Dover ]]></publisher-loc>
</nlm-citation>
</ref>
<ref id="B12">
<label>12</label><nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Callan]]></surname>
<given-names><![CDATA[C.G.]]></given-names>
</name>
<name>
<surname><![CDATA[Friedan]]></surname>
<given-names><![CDATA[D.]]></given-names>
</name>
<name>
<surname><![CDATA[Tseytlin]]></surname>
<given-names><![CDATA[A.A.]]></given-names>
</name>
</person-group>
<source><![CDATA[Nucl. Phys. B]]></source>
<year>1985</year>
<volume>262</volume>
<page-range>593</page-range></nlm-citation>
</ref>
<ref id="B13">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Callan]]></surname>
<given-names><![CDATA[C.G.]]></given-names>
</name>
<name>
<surname><![CDATA[Nappi]]></surname>
<given-names><![CDATA[C.R.]]></given-names>
</name>
<name>
<surname><![CDATA[Yost]]></surname>
<given-names><![CDATA[S.A.]]></given-names>
</name>
</person-group>
<source><![CDATA[Nucl. Phys. B]]></source>
<year>1987</year>
<volume>288</volume>
<page-range>525</page-range></nlm-citation>
</ref>
<ref id="B14">
<label>13</label><nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Rangel Orduña]]></surname>
<given-names><![CDATA[M.B.]]></given-names>
</name>
</person-group>
<source><![CDATA[Under graduate physics thesis]]></source>
<year>augu</year>
<month>st</month>
<day> 2</day>
<publisher-name><![CDATA[Facultad de Ciencias, UNAM]]></publisher-name>
</nlm-citation>
</ref>
</ref-list>
</back>
</article>
