The most recent edition of Ukulele Magazine featured an article on Ernest Ka’ai’s, the first ukulele pedagogue, who is also cited as being the first to standardize GCEA tuning for the ukulele in their methodology.
His first book, The Ukulele: A Hawaiian Guitar and How to Play It, was published in 1910. This would make it in the public domain–but I could not find it available online. So I contacted some universities that had it, and eventually ordred a copy from the University of Hawaii ($25 fee). I was interested to see how much ukulele instruction has changed in 107 years (the answer: a little).
For the sake of sharing this knowledge, I am sharing this PDF. Again, as this is a publication from 1910, I can share this with you legally.