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An economic survey of the Appalachian region, with special reference to agriculture
Coltrane, Robert Irvin, (1965)
A região a oeste da serra dos candeeiros : estudos económico-agricola dos concelhos de Alcobaca, Nazaré, Caldas da Rainha, Obidos e Peniche
Silva, Carlos da, (1961)
The East Jordan valley : a social and economic survey, 1961
(1961)