共 5 条
[1]
HANSEN PF, Patent No. 2219190
[2]
SPERLING K, IN PRESS
[3]
SPERLING KR, 1896, Patent No. 571487
[4]
SPERLING KR, 1975, ATOM ABSORPT NEWSL, V14, P60
[5]
SPERLING KR, Patent No. 2419936