Laurence M. Harwood; Leslie C. Hodgkinson; James K. Sutherland; Patrick Towers. Synthesis of anthracyclinones. Part 1. Regioselective alkylation of 5-hydroxyquinizarin. Canadian Journal of Chemistry. 1984, s. 1922–1925. DOI10.1139/v84-329.
Koichi Nakazawa; Shin Matsuura; Kosuke Kusuda. Studies on the Application of Polyphosphoric Acid as a Condensing Agent. II. Yakugaku Zasshi. 1954, s. 495–497. DOI10.1248/yakushi1947.74.5_495.
