The classical maximum principle is extended to the case where at frontier points the assumed global upper limit of the function is replaced by an upper limit along merely an arc, provided that the function does not have infinity as an asymptotic value.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
September 1967
Proc Natl Acad Sci U S A
May 1966
Proc Natl Acad Sci U S A
March 1964