Gega, P. C., Gega, P. C. S. i. e. e., & Gega, P. C. C. a. e. i. e. s. s. (1994). How to teach elementary school science (2nd ed.). Macmillan.

Gega, Peter C., Peter C. Science in elementary education Gega, and Peter C. Concepts and experiences in elementary school science Gega. How to Teach Elementary School Science. 2nd ed. New York: Macmillan, 1994.

Gega, Peter C., et al. How to Teach Elementary School Science. 2nd ed. Macmillan, 1994.