Assertion: fet | /r/HasProperty | invented by julius edgar lilienfeld
Facets:
value: in 1925
type: TEMPORAL
value: in 1934
type: TEMPORAL
value: by oskar heil
type: OTHER
Source sentences:
text: Field-effect transistors were invented by Julius Edgar Lilienfeld in 1925 and by Oskar Heil in 1934, but practical devices were not made until much later.