Rāingān phāk sombūn kānsamrūat r̄ængngān nai khēt chonnabot, Ph̨ō. S̨ō. 2509-2510 = Final report of the labor force survey, rural areas, 1966-1967 (Samnakngān Sathiti h̄æng Chāt, Samnak Nāyok Ratthamontrī, 1968)