Não informado. (1960). Agriculture in Northern Ireland. Department of Agriculture.
Chicago-referens (17:e uppl.)Não informado. Agriculture in Northern Ireland. Belfast, Irlanda: Department of Agriculture, 1960.
MLA-referens (8:e uppl.)Não informado. Agriculture in Northern Ireland. Department of Agriculture, 1960.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.