TY  - BOOK
AU  - Friedman A
TI  - Variational principles and free boundary problems
T2  - Pure and applied mathematics
U1  - B33, M2 
PY  - 1982///
CY  - New York    
PB  -  John Wiley and Sons     
KW  -  Boundary-value problem
KW  - Differential equations
ER  -