Jamie Etherington published a comprehensive and in-depth interview with Gordon Bok in the most recent issue of Fretboard Journal Magazine. While not available online, you can read about this issue and subscribe here: https://www.fretboardjournal.com/features/whats-inside-fretboard-journal-56-2/
They also offer a digital subscription as well here: https://shop.fretboardjournal.com/collections/downloads/products/fretboard-journal-digital-subscription-offer
