United States Patent 3504984
Inventors:
Bush, Walter R.
Publication Date:
04/07/1970
Other Classes:
385/117, 277/602, 2/422, 2/2.150, 405/186, 248/56, 362/570
International Classes:
G02B6/06; G02B6/38; G02B27/32; B63C11/00; G02B27/32; G02B5/14
Foreign References:
| GB449770A | | | | |
| GB1076538A | | | | |
| DE1103172B | | | | |
| DE1229748B | | | | |