Powers, D. L. (1987). Boundary value problems (3rd ed.). Harcourt Brace Jovanovich.
Cita Chicago (17th ed.)Powers, David L. Boundary Value Problems. 3rd ed. San Diego: Harcourt Brace Jovanovich, 1987.
Cita MLA (9th ed.)Powers, David L. Boundary Value Problems. 3rd ed. Harcourt Brace Jovanovich, 1987.
Atenció: Aquestes cites poden no estar 100% correctes.