Lua APA (7ú heag.)

Não informado. Virginia farm economics. Virginia Polytechnic Institute, Department of Agricultural Economics and Rural Sociology.

Lua i Stíl Chicago (17ú heag.)

Não informado. Virginia Farm Economics. Blacksburg, Va: Virginia Polytechnic Institute, Department of Agricultural Economics and Rural Sociology.

Lua MLA (8ú heag.)

Não informado. Virginia Farm Economics. Virginia Polytechnic Institute, Department of Agricultural Economics and Rural Sociology.

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