Research: "English guittar"
(18th c. cittern)
"English guittar" (18th c. cittern)
"English guittar" (18th c. cittern)
Additions and corrections Panagiotis Poulopoulos's The Guittar in the British Isles, 1750-1810 [external link].
Spreadsheet of sources of music for 18th century guittar, pianoforte guittar, cistre, & guitharre allemande. (Also see below.)