Assertion: accordion's keyboard | /r/HasProperty | added
Facets:
Source sentences:
text: With the Cover of the bellows the instrument can be duplicated, so the amount of Chords or single notes can be enlarged, or one can sound single notes, in this case, a second part with springs (free reeds) and also a second keyboard must be added, the bellows are in between these two parts, both hands push buttons and push and pull the bellows at the same time or alternatively.