[On the history of mechanical hearing aids].
Chumakov
F I
FI
LOR-otdelenie Moskovskogo oblastnogo nauchno-issledovatel'skogo klinicheskogo instituta.
Chkannikov
A N
AN
D004867:Equipment Design; D006310:Hearing Aids / Q000266:history*; D049669:History, 16th Century; D049670:History, 17th Century; D049671:History, 18th Century; D049672:History, 19th Century; D049673:History, 20th Century