Massen J, Lambert M, Schiestl M, Bugnyar T
CC BY 4.0
<a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4484978/bin/Video1.MP4">Video file</a> from <cite style="font-style:normal">Massen J, Lambert M, Schiestl M, Bugnyar T (2015). "<a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4484978">Subadult ravens generally don't transfer valuable tokens to conspecifics when there is nothing to gain for themselves</a>". <i>Frontiers in Psychology</i>. <a href="https://en.wikipedia.org/wiki/Digital_object_identifier" class="extiw" title="w:Digital object identifier">DOI</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.3389/fpsyg.2015.00885">10.3389/fpsyg.2015.00885</a>. <a href="https://en.wikipedia.org/wiki/PMID" class="extiw" title="w:PMID">PMID</a> <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pubmed/26175703">26175703</a>. <a href="https://en.wikipedia.org/wiki/PubMed_Central" class="extiw" title="w:PubMed Central">PMC</a>: <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4484978">4484978</a>.</cite>