Srobol Smutkupt. (2022) Applying Lean Six Sigma to Improve Telephone Bill Payment: A Case Study of A Real Estate Developer. <i>NIDA Case Research Journal</i>, <i>14</i>(2), 87-109.Srobol Smutkupt. "Applying Lean Six Sigma to Improve Telephone Bill Payment: A Case Study of A Real Estate Developer". NIDA Case Research Journal 14 (2022):87-109.Srobol Smutkupt. Applying Lean Six Sigma to Improve Telephone Bill Payment: A Case Study of A Real Estate Developer. National Institute of Development Administration:ม.ป.ท. 2022.