• [Wiki] http://en.wikipedia.org/wiki/Aegolius_funereus.
• [avibase] https://avibase.bsc-eoc.org/species.jsp?lang=EN&avibaseid=8AB4EAF6DBFA02CE&sec=lifehistory.
• [AnAge] https://genomics.senescence.info/species/entry.php?species=Aegolius_funereus.
• [CarlHorn1994] Carlsson, B.-G. and Hörnfeld, B. (1994). Determination of nestling age and laying date in Tengmalm's owl: Use of wing length and body mass. The Condor, 96(2):555–559. doi:doi:10.2307/1369336.
• [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.