Keep in mind that I couldn't verify the existence of a PDF version of "Fretboard Mastery." However, the book is widely available in print and e-book formats, and you may be able to find digital versions through online retailers or the author's website.
This section of the text aligns with the psychological concept of "audiation"—the process of mentally hearing and comprehending music. By pairing visual fretboard maps with audio exercises (often accessed via the accompanying audio tracks), Stetina forces the student to connect the sound of the interval with the shape on the neck. troy stetina fretboard mastery pdf
Websites like Amazon, GuitarMasteryMethod, or directly through Hal Leonard (if they are the publishers) might have the book available. You can find it in physical form or sometimes as an e-book. Keep in mind that I couldn't verify the