Ginsburg, H., & Opper, S. (1998). Pïaget's theory of intellectual development. UNESCO.
Chicago-čujuhus (17. p.)Ginsburg, Herbert, juo Sylvia Opper. Pïaget's Theory of Intellectual Development. París, Francia: UNESCO, 1998.
MLA-čujuhus (9. p.)Ginsburg, Herbert, juo Sylvia Opper. Pïaget's Theory of Intellectual Development. UNESCO, 1998.
Muitte dárkkistit čujuhemiid riektatvuođa, ovdal go geavahat daid iežat deavsttas.