Graaff, W. J. E. v. d. (1971). Three upper carboniferous, limestone-rich, high-destructive delta systems: With submarine fan deposits, Cantabrian Mountains, Spain. Rijksuniversiteit Groningen.
Lua i Stíl Chicago (17ú heag.)Graaff, Willem Jacob Evert van de. Three Upper Carboniferous, Limestone-rich, High-destructive Delta Systems: With Submarine Fan Deposits, Cantabrian Mountains, Spain. [Groningen: Rijksuniversiteit Groningen, 1971.
Lua MLA (8ú heag.)Graaff, Willem Jacob Evert van de. Three Upper Carboniferous, Limestone-rich, High-destructive Delta Systems: With Submarine Fan Deposits, Cantabrian Mountains, Spain. Rijksuniversiteit Groningen, 1971.
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