(App) Freeletics

Freeletics is a wonderful app that acts as your personal fitness trainer. It has a free introductory version and a full paid version. The free version is an excellent way get you started with the basics of calisthenics.

(Blog) 101nootropics.com

101 nootropics.com is a blog dedicated to nootropics (i.e substances and methods that improve cognitive function, particularly executive functions, memory, creativity, or motivation). It has a few good posts on calisthenics exercises.

(Blog) fitbodybuzz.com

fitbodybuzz.com is a fitness blog with lots of good advice on fitness in general and calisthenics in particular.