JAUN, Marlon A. Lean Six Sigma Techniques. Books on Demand, 2021. 194 p. ISBN 3754308122 .MALEYEFF, John.
OAKLAND, John S. and Robert J. OAKLAND. Total Quality Management and Operational Excellence. 5th ed. New York: Routledge, 2021. 517 p. ISBN 978-1-138-67340-0 .
Quality Service Management: A Guide to Improving Business Processes. New York, Routledge, 2022. 198 p. ISBN 9781032057514 .