Erki Tammiksaar; Sabine Brauckmann (2004). "Karl Ernst von Baer's 'Über Entwickelungsgeschichte der Thiere II' and its Unpublished Drawings". History and Philosophy of the Life Sciences. 26 (3/4): 291–308, 471–474. JSTOR23333718. PMID16302690.
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pubmed.ncbi.nlm.nih.gov
Erki Tammiksaar; Sabine Brauckmann (2004). "Karl Ernst von Baer's 'Über Entwickelungsgeschichte der Thiere II' and its Unpublished Drawings". History and Philosophy of the Life Sciences. 26 (3/4): 291–308, 471–474. JSTOR23333718. PMID16302690.