MLA

Extra, Guus, and Ludo Verhoeven. The Cross-linguistic Study of Bilingual Development. Amsterdam: Noord-Holland, 1994.

APA

Extra, G., & Verhoeven, L. (1994). The cross-linguistic study of bilingual development. Amsterdam: Noord-Holland.

Chicago

Extra, Guus ed., and Ludo Verhoeven ed. The Cross-Linguistic Study of Bilingual Development. Amsterdam: Noord-Holland, 1994.