APA (7th ed.) Citation

Madrigal, M. (1972). Open door to Spanish: [a conversation course for beginners]. Regents Publishing Co.

Chicago Style (17th ed.) Citation

Madrigal, Margarita. Open Door to Spanish: [a Conversation Course for Beginners]. New York: Regents Publishing Co, 1972.

MLA (9th ed.) Citation

Madrigal, Margarita. Open Door to Spanish: [a Conversation Course for Beginners]. Regents Publishing Co, 1972.