An essay on the construction of flutes, giving a history and description of the most recent improvements, with an explanation of the principles of acoustics applicable to the manufacture of wind instruments :
Boehm and Mendler #FCNY1 - Wood flute, offset G, open G#, reverse thum – Flute Center
The Inventor of the Bb thumb lever on the Böhm flute: Theobald Böhm or Giulio Briccialdi? | The Babel Flute
Flutes
Boehm System Flute – Duke University Musical Instrument Collections