Gega, P. C. (1994). Concepts and experiences in elementary school science (2nd ed.). Macmillan.
Cita Chicago (17th ed.)Gega, Peter C. Concepts and Experiences in Elementary School Science. 2nd ed. New York: Macmillan, 1994.
Cita MLA (9th ed.)Gega, Peter C. Concepts and Experiences in Elementary School Science. 2nd ed. Macmillan, 1994.
Atenció: Aquestes cites poden no estar 100% correctes.