Duff, P. M. (1993). Holmes' principles of physical geology (4th ed.). London: Chapman and Hall.
Παραπομπή Chicago StyleDuff, P. M. Holmes' Principles of Physical Geology. 4th ed. London: Chapman and Hall, 1993.
Παραπομπή MLADuff, P. M. Holmes' Principles of Physical Geology. 4th ed. London: Chapman and Hall, 1993.
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