1. Houben-Weyl, Methoden der Organischen Chemie (Georg Thieme Verlag, Stuttgart) Vol. IX.
2. W.A. Pryor, Mechanism of Sulfur Reactions (McGraw-Hill, New York, 1962).
3. S.R. Sandler and W. Karo, Organic Functional Groups Preparation (Academic Press, New York, 1968) Chapt. 18, p. 478.
4. E.E. Reid, Organic Chemistry of Bivalent Sulfur (Chemical Publishing Co., Inc., New York, 1960) Vols. II and III.
5. R.B. Wagner and H.D. Zook, Synthetic Organic Chemistry (John Wiley, New York, 1953) Chapt. 32, p. 787.