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Purdue University: Virtual Library Developmental Biology
A good resource for background into the entire scope of biological development. A list of terms will yield more depth on your choice.
Earth Life
Earth Life: The Placental Mammal and Reproduction
A very good site which covers the basics of mammal reproduction, in particular, placental mammals.
Earth Life
Earth Life: The Wonder of Milk
An interesting article on the production and value of mammalian milk. This is good insight into some of the critical factors affecting mammalian development.