When I started working in Supply Chain the book of Orlicky was a kind of bible. Of course it has been renewed a couple of times and still very valuable to understand how ERP/MRP-systems are working.
Purchasing was allways a part of Supply Chain but Purchase-people mostly argue that. There came a split in Purchasing between Contracting and Negotiation part and the call-off part which is often referred to as Procurement. Van Weele is the authority on Purchasing and wrote a lot of articles and books on that subject.
My first ‘teachers’ on Supply Chain were Ad van Goor and Klaas Boskma. Ad is retired now and Klaas died a while ago but I still remember their lessons. Klaas was more on Material Management and Ad more on Physical Distribution. That was the classic split at that time in what was called then ‘Logistics’ and nowadays ‘Supply Chain’. Logistics is basically now what was in the past called Physical Distribution.