Natchaya Chalaysap. 1996. Grammatically controlled English writing. Bangkok:National Institute of Development Administration;
Natchaya Chalaysap. (1996) Grammatically controlled English writing (รายงานผลงานวิจัย). National Institute of Development Administration:Bangkok.
Natchaya Chalaysap. Grammatically controlled English writing. Bangkok:National Institute of Development Administration, 1996.
Natchaya Chalaysap. (1996) Grammatically controlled English writing (รายงานผลงานวิจัย). National Institute of Development Administration:Bangkok.