Assertion: piano's keyboard | /r/HasProperty | developed by christopher donison
Facets:
value: in the 1970s
type: TEMPORAL
Source sentences:
text: A 15/16 size (152 mm (6.0 in) octave span) and the 7/8 DS Standard (140 mm (5.5 in) octave span) keyboard developed by Christopher Donison in the 1970s and developed and marketed by Steinbuhler & Company.