• [Wiki] http://en.wikipedia.org/wiki/Zonotrichia_capensis.
• [avibase] https://avibase.bsc-eoc.org/species.jsp?lang=EN&avibaseid=3647E146F88AE943&sec=lifehistory.
• [AnAge] https://genomics.senescence.info/species/entry.php?species=Pooecetes_gramineus.
• [DawsEvan1960] Dawson, W. R. and Evans, F. C. (1960). Relation of growth and development to temperature regulation in nestling vesper sparrows. The Condor, 62(5):329--340.
• [Kooy2010] Kooijman, S. (2010). Dynamic Energy Budget theory for metabolic organisation. Cambridge Univ. Press, Cambridge.
• [PrinPres1991] Prinzinger, R., A.Preßmar, and Schleucher, E. (1991). Body temperature in birds. Comp. Biochem. Physiol., 99A(4):499--506. doi:10.1016/0300-9629(91)90122-S.