APA (7th ed.) Citation

Marm, I., & Sommerfelt, A. A. (1971). Norwegian: A book of self-instruction in the Norwegian Riksmål. Teach Yourself Books.

Chicago Style (17th ed.) Citation

Marm, Ingvald, and Alf Axelssøn Sommerfelt. Norwegian: A Book of Self-instruction in the Norwegian Riksmål. London: Teach Yourself Books, 1971.

MLA (9th ed.) Citation

Marm, Ingvald, and Alf Axelssøn Sommerfelt. Norwegian: A Book of Self-instruction in the Norwegian Riksmål. Teach Yourself Books, 1971.