Assertion: overhead projector | /r/HasProperty | 3m
Facets:
Source sentences:
text: Overhead Projector: 3M, Elmo, WolfVision, Liesegang?
text: Roger Appledorm, a research scientist for one of the first major manufactures of overhead projectors 3M, is widely attributed to developing the thermo-fax copying process and later a machine that could copy into projection transparencies.