Ech-Cherif El-Kettani Hamza
Lev Nikolaevich Ovchinnikov
V. M. Overchuk
Sunagawa, Ichirō.
Richard H. Shiley
Amos Peaslee Brown
Imperial Institute (Great Britain)
K. P. Ivanov
I. B. Seravkin
John James Prucha
George William Plummer
Imperial Institute, London. Mineral Resources Department.
Martin B Goldhaber
P.V Pankrat'ev
M. R Stanton
Aleksandr Sergeevich Bobokhov
Bohuslav Cambel
Unknown Author
Ch. D. Dzhafarov
Jose de Jesus Gomez Reggio