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Berg, Karl S.; Delgado, Soraya; Okawa, Rae; Beissinger, Steven R.; Bradbury, Jack W. (January 2011). "Contact calls are used for individual mate recognition in free-ranging green-rumped parrotlets, Forpus passerinus". Animal Behaviour. 81 (1): 241–248. Bibcode:2011AnBeh..81..241B. doi:10.1016/j.anbehav.2010.10.012.
"Online Etymology Dictionary". Archived from the original on 28 September 2008. Retrieved 20 September 2008.; The asterisk before a word indicates that it is a hypothetical construction, not an attested form.
"Online Etymology Dictionary". Archived from the original on 28 September 2008. Retrieved 20 September 2008.; The asterisk before a word indicates that it is a hypothetical construction, not an attested form.
"personal name". Merriam-Webster.com. Merriam-Webster. Archived from the original on 19 June 2018. Retrieved 18 June 2018.