TY  - BOOK
AU  - Mitchell,J.V.
TI  - Principles of navigation / 
U1  - 623.89 23
PY  - 1973///.
CY  - London : 
PB  - Mayflower trading co. ltd, 
KW  - The prime vertical problem.
KW  - Time calculation.
KW  - Miscellaneous problems.
ER  -