BACK-UP Perspective

Holtes & Sietsma is the pseudonym of the Dutch authors Bert Holtes and Wop Sietsma. Both authors were born in 1957, Bert in Alkmaar and Wop in Sneek. Bert spent his working life as a pastry chef, marine, police officer, entrepreneur and manager in various industries, while Wop worked as a secretary and as an independent IT worker in the computer world before they both began enjoying their free time. They are the joint authors of the fictional thriller series BACK-UP.