APA (7th ed.) Citation

Wartburg, W. v., & Ullmann, S. (1969). Problems and methods in linguistics. blackwell.

Chicago Style (17th ed.) Citation

Wartburg, Walter von, and Stephen Ullmann. Problems and Methods in Linguistics. Oxford: blackwell, 1969.

MLA (9th ed.) Citation

Wartburg, Walter von, and Stephen Ullmann. Problems and Methods in Linguistics. blackwell, 1969.