http://www.designntrend.com/articles/20151/20140925/regenerating-brain-neurons-help-birds-sing-better-during-breeding-season.htm
http://www.counselheal.com/articles/11475/20140924/dying-brain-cells-cue-new-grow-songbird-study-finds.htm
http://www.washington.edu/news/2014/09/23/dying-brain-cells-cue-new-brain-cells-to-grow-in-songbird/
http://www.daijiworld.com/news/news_disp.asp?n_id=266014
