1. Allen C. W. Astrophysical Quantities 2 (1963).
2. EVANS, N.J., MICROWAVE ABSORPTION OF 212-!211 ROTATIONAL TRANSITION IN INTERSTELLAR FORMALDEHYDE, ASTROPHYSICAL JOURNAL 159: L9 (1970).
3. HABING, H.J., INTERSTELLAR RADIATION DENSITY BETWEEN 912 A AND 2400 A, BULLETIN OF THE ASTRONOMICAL INSTITUTES OF THE NETHERLANDS 19: 421 (1968).
4. Microwave Detection of Thioformaldehyde
5. KURT, V.G., OBSERVATIONS AND INTERPRETATION OF ULTRAVIOLET RADIATION OF GALAXY, SOVIET ASTRONOMY AJ USSR 11: 928 (1968).