TY  - DATA
AU  - Beem, John K.
AU  - Woo, Peter Y.
TI  - Doubly timelike surfaces 
T2  - Memoirs of the American Mathematical Society, 
SN  - 9781470400422 (online)
PY  - 1969///
CY  - Providence, R.I.
PB  - American Mathematical Society
UR  - http://www.ams.org/memo/0092
ER  -