Sources for FLAC Music

Hi! I wanted to start to hoard my favorite tracks in the best possible quality. A lot of stuff is available through Deezer or Tidal i know, but what sources are you guys using when FLACs for particular albums or songs cannot be found on Deezer or Tidal? I wanted to get the Rock n Roll Train song from ACDC in FLAC, but Tidal doesn't have it in FLAC.

Are there any good Public/Private trackers for Music?

Cheers.