TY  - BOOK
AU  - Heading,John
TI  - An introduction to phase-integral methods
T2  - Methuen's monographs on physical subjects
U1  - 517.38 
PY  - 1962///
CY  - London, New York
PB  - Methuen, Wiley
KW  - Differential equations, Linear
KW  - Numerical solutions
KW  - Integrals
KW  - Mathematical physics
N1  - Includes bibliography
ER  -