TY  - BOOK
AU  - Lewellen,John Bryan
TI  - Helicopters: how they work
AV  - TL716 .L48
U1  - 629.13335  629.1335* 
PY  - 1954///]
CY  - New York
PB  - Crowell
KW  - Helicopters
UR  - http://www.archive.org/details/helicoptershowth00lewe
UR  - http://www.openlibrary.org/books/OL6155469M
ER  -