The following files are from or contain content from external sources:

app/src/main/assets/GeneralUser GS v1.471.sf2
Source: http://schristiancollins.com/generaluser.php
License: GeneralUser GS License v2.0 (app/src/main/assets/LICENSE.txt)

app/src/main/res/drawable/ic_banjo_icon.xml
Source: https://thenounproject.com/icon/banjo-1352765/
License: Creative Commons CC BY 3.0

app/src/main/res/drawable/ic_guitar_icon.xml
Source: https://thenounproject.com/icon/guitar-1352777/
License: Creative Commons CC BY 3.0

app/src/main/res/drawable/ic_mandolin_icon.xml
Source: https://thenounproject.com/icon/mandolin-1352775/
License: Creative Commons CC BY 3.0

app/src/main/res/drawable/ic_ukulele_icon.xml
Source: https://thenounproject.com/icon/ukelele-1352787/
License: Creative Commons CC BY 3.0

sherlockmidi/
Source: https://github.com/bmaupin/MidiDriver
License: Apache 2.0, GPL 2.0 with classpath exception
