I have found that the printed OPERA XX (Op.20) does not agree with the Opus numbers on the page www.uquebec.ca. Boccherini's works have been catalogued by the French musicologist Yves Gérard (born 1932) in the Gérard catalog, published in London (1969), hence the "G" numbers applied to his output. The Key's and movement titles match those of Op.13.
