https://www.musictheory.net/ – Music Theory/Ear Training
http://stringskills.com/ . -Scales/Arpeggios/Shifting Exercises.
https://imslp.org/ – Public Domain Music Database
http://www.dronetonetool.com/ – Reference Tones for Practice
Suggested Apps
-Pro Metronome – Metronome App
-PitchLab – Tuner App
-Tenuto – Theory Practice App