Timekeeping instruments. Watch external parts made of hard materials. General requirements and test methods
1991 ◽
Vol 49
◽
pp. 408-409
1984 ◽
Vol 45
(C8)
◽
pp. C8-315-C8-324
◽
1990 ◽
Vol 64
(03)
◽
pp. 478-484
◽
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