wikipedia.org/wiki/Digital_object_identifier" title="Digital object identifier">doi</a>:<a rel="nofollow" class="external text" href="http://dx.doi.org/10.1126%2Fscience.287.5461.2196">10.1126/science.287.5461.2196</a>. <a href="//en.wikipedia.org/wiki/PubMed_Identifier" title="PubMed Identifier" class="mw-redirect">PMID</a>&#160;<a rel="nofollow" class="external text" href="//www.ncbi.nlm.nih.gov/pubmed/10731133">10731133</a>.</span><span title="ctx_ver=Z39.88-2004&amp;rfr_id=info%3Asid%2Fen.wikipedia.org%