A. F. M. ter Elst, A. Linke and J. Rehberg: On the numerical range of sectorial forms (PAFA)
	Volume 7, Number 5, 1929-1938 On the numerical range of sectorial forms A. F. M. ter Elst, A. Linke and J. Rehberg    ONLINE SUBSCRIPTION (Library Only) PDF   PDF   Open Access (Free) Html   Flash              Copyright © 2022 Yokohama Publishers