The Biological Problem of To-day :
Hertwig, Oscar
The Biological Problem of To-day : Preformation Or Epigenesis? The Basis of a Theory of Organic Development [electronic resource] / Oscar Hertwig - Project Gutenberg, 2011 - Project Gutenberg 37221 .
Public domain in the USA.
Electronic text
The Biological Problem of To-day : Preformation Or Epigenesis? The Basis of a Theory of Organic Development [electronic resource] / Oscar Hertwig - Project Gutenberg, 2011 - Project Gutenberg 37221 .
Public domain in the USA.
Electronic text