everything on this site has a source. here they are.
official blizzard
Patch notes, official announcements, and expansion news.
Blue posts — official Blizzard responses across forum categories.
Hotfix notes, maintenance windows, and PTR updates.
talent builds
M+ talent builds sampled from top players. Consensus builds require 60%+ agreement across the top 50 players per spec.
Raid build data drawn from top parse rankings per spec.
dungeon & raid guides
Boss mechanics, ability references, and encounter data for dungeons and raids.