Combined reading glass, light and compass
作者： Kenneth W Pfleger
DOI:
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摘要:
lens.org 参考文章(3)
George F Grebey, Virginia G Anthony, Pen light or the like with adjustable head ,(1954)
Clarence M Flint, Jr Brian O'brien, Inspection device for determining height of dots on engraved plates ,(1950)
Liftschitz Benjamin Daniel, Electric pocket lamp ,(1934)