Srobol Smutkupt และ Umaporn Naratornsawatdikul. (2019) An Improvement of Delivery Lead Time: A Case Study of a Trading Company. <i>Humanities, Arts and Social Sciences Studies</i>, <i>19</i>(3), 616-627.Srobol Smutkupt และ Umaporn Naratornsawatdikul. "An Improvement of Delivery Lead Time: A Case Study of a Trading Company". Humanities, Arts and Social Sciences Studies 19 (2019):616-627.Srobol Smutkupt และ Umaporn Naratornsawatdikul. An Improvement of Delivery Lead Time: A Case Study of a Trading Company. Silpakorn University Research, Innovation and Creativity Administration Office:ม.ป.ท. 2019.