APA (7th ed.) Citation

Focke, H. (1977). Perturbation methods for symmetric operators.

Chicago Style (17th ed.) Citation

Focke, Heinz. Perturbation Methods for Symmetric Operators. 1977.

MLA (9th ed.) Citation

Focke, Heinz. Perturbation Methods for Symmetric Operators. 1977.

Warning: These citations may not always be 100% accurate.