APA aipamena

FREDRICHS K O. (1965). PERTURBATION OF SPECTRA IN HELBERT SPACE. -.

Chicago Style aipamena

FREDRICHS K O. PERTURBATION OF SPECTRA IN HELBERT SPACE. -: -, 1965.

MLA aipamena

FREDRICHS K O. PERTURBATION OF SPECTRA IN HELBERT SPACE. -, 1965.