TY  - BOOK
AU  - Weinstein, Alexander.
AU  - Stenger, William.
TI  - Methods of intermediate problems for Eigenvalues: : theory and ramifications
T2  - Mathematics in science and engineering
U1  - 517.4 
PY  - 1972///
CY  - New York
PB  - Academic Press
KW  - Cálculo de variaciones
ER  -