Don't Make This Silly Mistake With Your 구글 상위 노출
https://www.evernote.com/shard/s391/sh/d57ffe1a-515f-46c1-ac55-5a66921aad2b/0a7b70f4dada4da5afd64804735d3871
PDFs could be emailed and distributed around the web, Therefore if there is valuable data in them, it is extremely very likely they're going to spread like wildfire, by e-mail, teams, chat rooms and web forums.