Lua APA (7ú heag.)
Ginsburg, H., & Opper, S. (1979). Piaget's theory of intellectual development (2d ed.). Prentice-Hall.
Lua i Stíl Chicago (17ú heag.)
Ginsburg, Herbert, agus Sylvia Opper. Piaget's Theory of Intellectual Development. 2d ed. Englewood Cliffs, N.J.: Prentice-Hall, 1979.
Lua MLA (9ú heag.)
Ginsburg, Herbert, agus Sylvia Opper. Piaget's Theory of Intellectual Development. 2d ed. Prentice-Hall, 1979.
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