There are a lot of good resources for Facility Managers out there! Some are in the context of e-books, others in the form of groups, and online resources. I’ll just point out a few that I know of.
IFMA is a great resource for facility managers around the globe. They are highly trusted and also hold several facility management conferences around the world. I highly suggest attending if you have not before! PS I have no affiliation to them, just a happy member.
1 – IFMA E-Book
1 – What is Facility Management