Hoyle, Fred
Frontiers of astronomy
Harper & Brothers, 1955
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Morrison, David
Frontiers of astronomy
Saunders College, 1990
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Silverberg, Robert
Frontiers in archeology
Chilton Book, 1966
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Taylor, Verta
Feminist frontiers
McGraw-Hill, 2009
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McCoubrey, Hilaire
International organizations and civil wars
Brookfield Dartmouth , 1995
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