[Items in red are forthcoming.]
Additions and corrections to 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.)
Information on strings for English guittar
Information on strings for French cistre/guittare allemande