1. H. G. Leemann, K. Stich and M. Thomas, Progress in Drug Research, vol. 6 (Birkhäuser Verlag, Basel 1963 ), p. 151.
2. H. H. Seliger and W. D. McElroy, Light: Physical and Biological Action ( Academic Press, New York 1965 ).
3. J. B. Thomas, Primary Photoprocesses in Biology (North-Holland Publishing Co., Amsterdam).
4. Photochemistry and Photobiology 1 (1962).
5. Advances in Photochemistry, vol. 1–3 (Interscience Publishers Inc., New York 1963– 1964).