1. A. Wada, C. Nakajima, T. Hironaka, Jpn. Kokai Patent 50-111,034 (1975).
2. E.J. Strojny, US Patent 4,328,373 (1982).
3. A.P. Gilbein, R. Hansen, US Patent 4,585,899 (1986).
4. Selective Reduction of Acetic Acid to Acetaldehyde on Iron Oxides
5. F. Wattimena, H.J. Heijiman, Eur. Patent 101,111 (1983).