1. Abdulsaleh, Abdulaziz M, Andrew C Worthington (2013) Small and medium-sized enterprises financing: a review of literature. Int J Bus Manag 8(14). Citeseer, 36
2. Aboelmaged MG (2011) Reconstructing six sigma barriers in manufacturing and service organizations: the effects of organizational parameters. Int J Qual Reliab Manag 28(5):519–541. https://doi.org/10.1108/02656711111132562
3. Albliwi SA, Antony J, Abdul S, halim (2015) A systematic review of lean six sigma for the manufacturing industry. Emerald Group Publishing Limited, Bus Process Manag J
4. Ali, Yousaf, Ahsan Younus, Amin Ullah Khan, Hamza Pervez (2020) Impact of lean, six sigma and environmental sustainability on the performance of SMEs. Int J Prod Perform ManagementBus Manag Stud. Emerald Publishing Limited
5. Al-Shamkhani, Maher, Ahmed K Elshennawy (2013) Application of six sigma methodology to reduce environmental and economic impacts of discharging the produced water in Southern Iraqi oil fields. J Manag & Eng Integr 6(2). International Conference on Industry, Engineering, & Management Systems, 31