selected cantatas the table used abbreviations : s = soprano , ms = mezzo-soprano , a = alto , t = tenor , bar = baritone , b = bass , childr = children 's choir , str = strings , instr = instruments , tr = tromba ( trumpet ) , co = horn , cn = cornett , tb = trombone , ti = timpani , fl = recorder , ft = flauto traverso , ob = oboe , oa = oboe d'amore , oc = oboe da caccia , vn = violin , va = viola , vc = cello , fg = bassoon , org = organ ) , bc = basso continuo literature alfred dürr : johann sebastian bach : die kantaten .