"external-link">c</a></span><span class="op">(</span></span>
<span>  <span class="va">source_means_c</span><span class="op">[</span>, <span class="st">"meand15NPl"</span><span class="op">]</span> <span class="op">-</span> <span class="va">source_sds_c</span><span class="op">[</span>, <span class="st">"SDd15N"</span><span class="op">]</span>,</span>
<span>  <span class="va">source_means_c</span><span class="op">[</span>, <span class="st">"meand15NPl"</span><span class="op">]</span> <span class="op">+</span> 