TY  - GEN
AU  - DUFFETT-SMITH
TI  - Practical astronomy with your calculator
SN  - 0-521-28411-2
AV  - QB62.5.D83 
PY  - 1981///
CY  - New York
PB  - Cambridge University Press
KW  - Astronomy-problems, exerises
KW  - Calculating machines
ER  -