Physically meeting with original developer or author, is always the best way to obtain and distribute and verify and trust PGP/GPG Keys with highest trust level, and will remain as the best level of best trustworthy way. Publishing of GPG/PGP full Key or full Key fingerprint on/with widely known (physical/paper-material based) book, by the original author/developer, is the 2nd best form of sharing trustworthy key with and for users. Before meeting a developer or author, users should research on their own on the developer or author in book library and via internet, and aware of developer's or author's photo, work, pub-key fingerprint, email-address, etc.