Colojoara, Ion Theory of generalized spectral operators by Ion Colojoara and Ciprian Foias - New York Gordon and Breach Science Publishers 1968 - xvi, 232 p. ; 24 cm. - Mathematics and its applications v.9 . Bibliography: p. 220-226. LCCN: 68-024488 Subjects--Topical Terms: Spectral theory (Mathematics)