Frontier Society
Martinus Njhoff, 1971
Buku Teks
Cole, John W.
The Hidden frontier
Academic Press, 1974
Buku Teks
Dobson, Rosemary
Over the frontier
Angus & Robertson, 1978
Buku Teks SO
Kokot, Jozef
The logic of the Oder-Neisse frontier
Wydawnictwo Zachodnie, 1957
Buku Teks
Oceanography the last frontier
edited by Richard C. Vetter
Voice of America, 1974
Buku Teks