एपीए उद्धरण

David D Wooldridge. (1990). Manual on land use survey and capability classification for upland watersheds. Philippines: Asean-US watershed Project.

शिकागो स्टाइल उद्धरण

David D Wooldridge. Manual On Land Use Survey and Capability Classification for Upland Watersheds. Philippines: Asean-US watershed Project, 1990.

एमएलए उद्धरण

David D Wooldridge. Manual On Land Use Survey and Capability Classification for Upland Watersheds. Philippines: Asean-US watershed Project, 1990.