Shrock, R. R. (1966). A cooperative plan in geophysical education: The GSI student cooperative plan : the first fifteen summer programs, 1951-1965. Geophysical Service Inc.
Lua i Stíl Chicago (17ú heag.)Shrock, Robert R. A Cooperative Plan in Geophysical Education: The GSI Student Cooperative Plan : The First Fifteen Summer Programs, 1951-1965. Dallas, Texas: Geophysical Service Inc, 1966.
Lua MLA (9ú heag.)Shrock, Robert R. A Cooperative Plan in Geophysical Education: The GSI Student Cooperative Plan : The First Fifteen Summer Programs, 1951-1965. Geophysical Service Inc, 1966.
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