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Publication of YU216271ApublicationCriticalpatent/YU216271A/xx
Publication of YU34074BpublicationCriticalpatent/YU34074B/xx
H04M1/00—Substation equipment, e.g. for use by subscribers
H04M1/02—Constructional features of telephone sets
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Engineering & Computer Science
(AREA)
Signal Processing
(AREA)
Telephone Set Structure
(AREA)
YU216271A1970-08-261971-08-24Exponentially formed sound conductor for electro-acoustic transverters at telephone apparatus which emits a two-frequency tone call
YU216271A
(en)