共 20 条
- [1] BABCOCK SH, 1948, Patent No. 2441949
- [2] BABCOCK SH, 1945, Patent No. 2375885
- [3] BERGEL F, 1947, Patent No. 2423062
- [5] BEUTEL RH, 1949, Patent No. 2474719
- [6] FINKELSTEIN J, 1943, Patent No. 2328000
- [7] Flint R. B., 1935, U.S. Patent, Patent No. [US2016962, 2016962]
- [8] HARRIS SA, 1943, Patent No. 2319545