APA (7th ed.) Citation

Eberhard, W., Freiling, G., & Schneider, A. (1989). Expansion theorems for a class of regular indefinite eigenvalue problems.

Chicago Style (17th ed.) Citation

Eberhard, Walter, Gerhard Freiling, and Albert Schneider. Expansion Theorems for a Class of Regular Indefinite Eigenvalue Problems. Duisburg, 1989.

MLA (9th ed.) Citation

Eberhard, Walter, et al. Expansion Theorems for a Class of Regular Indefinite Eigenvalue Problems. 1989.