TY  - BOOK
AU  - Keyfitz,Nathan
AU  - Beekman,John A.
TI  - Demography through problems
SN  - 0387908366
PY  - 1984///
CY  - New York
PB  - Springer-Verlag
KW  - Demography
KW  - Problems, exercises, etc
N1  - Bibliography : p.135-136
ER  -