Big resources on precision lapping

I've been delving into lapping at work and like many places the knowledgeable people already retired.

Kind of feeling lucky to have hand lapped a part to 1.3 micron flatness (checked with a zygo) since I really don't have a great grasp on the technologies and processes. One thing that worries me is upkeep/maintenance of the plates. I've heard of plates being as bad as .010" out of flat.

Just wanted to share some of the reading that I've done to learn more about the lapping process.

Another source from Kemet.
https://www.kemet.co.uk/blog/lapping