Castillo, M. T. (1999). On the existence of the essential spectrum for a class of differential expressions. Matimya's Matematika.
Chicago Style (17th ed.) CitationCastillo, Maritina T. "On the Existence of the Essential Spectrum for a Class of Differential Expressions." Matimya's Matematika 1999.
MLA (9th ed.) CitationCastillo, Maritina T. "On the Existence of the Essential Spectrum for a Class of Differential Expressions." Matimya's Matematika, 1999.
Warning: These citations may not always be 100% accurate.