1. Conklin, Edwin G.: The embryology ofFulgur. A study of the influence of yolk an development. Proc. Acad. nat. Sci. Philad.59, 320?359 (1907).
2. Cellular differentiation. Sec. IX of General Cytology, University of Chicago Press (1924).
3. Crabb, Edward D.: Anatomy and function of the reproductive system in the snail,Lymnaea stagnalis appressa Say. Biol. Bull. Mar. biol. Labor. Wood's Hole53, 55?66 (1927).
4. Egg laying and birth of young in three species ofViviparidae. Nautilus42, 125?128(1929).
5. Crabb, Edward D. a.Crabb, Ruby M.: Polyvitelliny in pond snails. Biol. Bull. Mar. biol. Labor. Wood's Hole53, 318 bis 326 (1927).