Chromatography course at University College of London, book here:
https://www.ucl.ac.uk/biochemical-engineering/research/mbi/courses/dpc
ICH Guidelines - ICH Official web site:
https://www.ich.org/page/ich-guidelines
Cytiva Handbooks for Chromatography resins:
Handbooks | Cytiva (cytivalifesciences.com)
Highly essential book on Validation of Processes (must have):
Process Validation in Manufacturing of Biopharmaceuticals, third edition
Edited by: Anurag S. Rathore and Gail Sofer
ISBN: 978-1-4398-5093-0