Soils of Cagayan, Isabela, Negros Occidental, and Nueva Vizcaya. - [Philippines (Commonwealth) Department of Agriculture and Commerce (Manila [s.n.)
[v.1] Cagayan -- [v.2] Isabela -- [v.3] Negros Occidental -- [v.4] Nueva Viscaya.
Arbitrarily numbered.
Keywords: Soils -- Philippines -- Cagayan; Soils -- Philippines -- Isabela; Soils -- Philippines -- Negros Occidental; Soils -- Philippines -- Nueva Vizcaya