1. Leonardo da Vinci;Nicholl,2004
2. Leonardo da Vinci on the human body;O’Malley,1952
3. The drawings of Leonardo da Vinci;Popham,1946
4. Über Entwickelungsgeschichte der Thiere;von Baer,1828
5. E.B. Wilson's “destruction” of the germ-layer theory;Baxter;Isis,1977