1. bassClef.svg: https://openclipart.org/detail/12475/bass-clef
2. trebleClef.svg : https://openclipart.org/detail/12473/treble-clef
3. blackflat.svg: https://openclipart.org/detail/198043/mono-music-flat
4. blacksharp.svg: https://openclipart.org/detail/198039/mono-music-cross
5. half-note.svg: https://openclipart.org/detail/92971/half-note-stem-facing-up
6. quarter-note.svg: https://openclipart.org/detail/92875/quarter-note-stem-facing-up
7. eighth-note.svg: https://openclipart.org/detail/92869/eighth-note-stem-facing-up
8. whole-note.svg: https://openclipart.org/detail/140893/whole-note
