1. Rubidium/strontium ages from the Western Transvaal;Allsopp;Nature,1964
2. The Geology of Some Ore Deposits in Southern Africa;Brock;Geol. Soc. S. Afr. (Publ.),1964
3. Origins of photosynthesis;Echlin;Science Journal,1966
4. The Biology of Lichens;Hale,1967
5. The Biology of Lichens;Hale,1967