@Stormonu I would definitely keep any Volo Guides. The information is sooo damn useful from a roleplaying perspective. One could even use them in a 1490 Realms game. I seriously doubt that any PC would know or care that any NPC that you are using should have died 80 years ago
I'm thinking about doing a deep dive into BECMI. I bought the Boxsets(B,E,C,M,I) in PDF form from drivethru a couple of months ago after watching some BECMI Berserker vids on YouTube. Guess it's time to get the GAZ Series, and the Adventures and really get to know the material.