TY  - GEN
AU  - Billings,J J
TI  - Ovulation method of contraception
SN  - 0025-729X
PY  - 1981///0521
KW  - Female
KW  - Humans
KW  - Natural Family Planning Methods
N1  - Publication Type: Letter
UR  - https://doi.org/10.5694/j.1326-5377.1981.tb135299.x
ER  -