FR939303A
(en )
1948-11-09
Improvements to electro-magnetic devices
FR858513A
(en )
1940-11-27
Improvements to mechanical exploration devices for sound recordings
FR854732A
(en )
1940-04-23
Improvements to devices for eliminating unwanted electrical signals
FR860843A
(en )
1941-01-24
Improvements to devices for recording sounds
FR856854A
(en )
1940-08-13
Devices for sound translation
BE435751A
(en )
1939-08-31
Improvements to mechanical exploration devices for sound recordings
FR846487A
(en )
1939-09-18
Improvements to talking machines
FR852767A
(en )
1940-03-02
Improvements to electro-magnetic sound recording devices
FR971517A
(en )
1951-01-18
Improvements to acoustic damping devices
FR843236A
(en )
1939-06-28
Improvements to crystal type sound reproducing devices
FR849359A
(en )
1939-11-22
Improvements to devices to reduce vibrations
FR856373A
(en )
1940-06-12
Improvements to inertial actuated devices
FR850393A
(en )
1939-12-15
Improvements to acoustic converters
FR858616A
(en )
1940-11-29
Improvements to amplifiers
FR848252A
(en )
1939-10-26
Improvements to pipe assembly devices
FR844211A
(en )
1939-07-20
Improvements to sound reproducing devices such as loudspeakers
FR853667A
(en )
1940-03-26
Improvements to sound recording devices
FR854163A
(en )
1940-04-06
Improvements to graphic recording devices
FR853247A
(en )
1940-03-13
Improvements to audio-frequency amplifiers
FR876922A
(en )
1942-11-23
Improvements to magnetic suspension devices
FR855048A
(en )
1940-04-30
Improvements to ultrasonic projectors
FR972124A
(en )
1951-01-25
Improvements to reduced-format sound films
FR867164A
(en )
1941-10-03
Improvements to carburettor devices
FR884414A
(en )
1943-08-12
Improvements to sound recordings
FR841120A
(en )
1939-05-10
Improvements to recording manometers