Singh, B. (1988). International symposium on underground engineering, 14-17 April, 1988, New Delhi, India: Proccedings. Rotterdam: A. A. Balkema.
Παραπομπή Chicago StyleSingh, B. International Symposium On Underground Engineering, 14-17 April, 1988, New Delhi, India: Proccedings. Rotterdam: A. A. Balkema, 1988.
Παραπομπή MLASingh, B. International Symposium On Underground Engineering, 14-17 April, 1988, New Delhi, India: Proccedings. Rotterdam: A. A. Balkema, 1988.
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