Like Oracle company, its employees, creates good books on Oracle. And as i know the learning source for Outsystems is so widely spread with a wide spectrum of technologies that is hard to be on the right track for a beginner (like me) in a web/mobile application.
Hopefully, Outsystems encourage its experts to publish books on Outsystems - Outsystems Javascript cookbook, OS Google Map cookbook, OS security cookbook, os tuning cookbook... etc.
best regards,
bb