"Op. post." . "Op. 62" . "Opus 16" . "S. 141" . "cataloging" . "opus number" . "Op.28" . "Opus 7" . "opus 3" . "op." . "WoO." . . "oeuvre" . "Op. 44" . "opp." . "Opp" . "Op" . "Op. 48" . "op" . . "w/o op." . "catalogue" . "opus-numbered" . "a" . "catalog number" . "op. 24" . "Op. 6" . "Op. 20" . "Opus" . "Op. 13" . . "Op. posth." . "Op. 64" . "Op. " . "Opus number" . "Opus number" . "Op. 23" . "Opp." . . "opus" . "Op. 1" . "Opus works" . "Op. 68" . "works" . "Op." . "compositions" . "Op. 60" . "Op. 66" . "opuses" . "complex of works" . "FWV" . .