Ilyin, A.V. (September 1978). "Comment on "The July 9 and 23, 1905, Mongolian earthquakes, a surface-wave investigation" by Emile Okal". Earth and Planetary Science Letters. 41 (1): 107–109. Bibcode:1978E&PSL..41..107I. doi:10.1016/0012-821X(78)90047-X.
Ilyin, A.V. (September 1978). "Comment on "The July 9 and 23, 1905, Mongolian earthquakes, a surface-wave investigation" by Emile Okal". Earth and Planetary Science Letters. 41 (1): 107–109. Bibcode:1978E&PSL..41..107I. doi:10.1016/0012-821X(78)90047-X.