Have a look at the blog from David Billouz on AXELOS website at the address : https://www.axelos.com/news/blogs/january-2020/service-desk-heart-of-itil-4s-service-value-chain

Have a look at the blog from David Billouz on AXELOS website at the address : https://www.axelos.com/news/blogs/january-2020/service-desk-heart-of-itil-4s-service-value-chain