Mixing and Mastering:
Mixing Secrets for the Small Studio: https://mega.nz/#!dNtARY5Q!bfm7xOeRcRilrs3qkP-DAFUUKBW4DEcGQ_IR_PWkYo0
Mixing Engineers Handbook: https://mega.nz/#!YUkgCJpR!bTX1gzqhD7fozTipk4XsRNiWQmHQXBx0T4pHMRvaURw
The Secret of the Mastering Engineer, Bob Katz: https://mega.nz/#!ZAE2EBCb!r0Hf0gho8pL7BlBJ6-6rJznB9SEhCG31NzNJUJX34tU
Audio Engineering and Acoustics ebook bundle: https://mega.nz/#!wEVAVbgB!hwd7vmzaZ9C6wAnVbqIQt37pNUpfpn0t2ecSjZGRNe4
(Bobby Owsinski - The Mixing Engineer's handbook 4th edition, The Recording Engineer's handbook 4th edition, The Mastering Engineer's handbook 4th edition. Timothy Dittmar - Audio Engineering 101, William Moylan - The Art of Recording, F. Alton Everest - Master Handbook of Acoustics, Rod Gervais - Home Recording Studio: Built It Like The Pros, 2nd Edition, Philip Newell - Recording Studio Design

Theory and Composition:
Music theory for musicians and normal people:
http://tobyrush.com/theorypages/index.html
tl:dr Music Theory:
https://gumroad.com/l/tldrmusic

Synthesizers and synthesis:
http://www48.zippyshare.com/v/20999348/file.html
https://www.youtube.com/watch?v=atvtBE6t48M
https://www.youtube.com/watch?v=NMF8F9z7Zr8
http://beausievers.com/synth/synthbasics/
http://www.analogindustries.com/b1764/