Qingshan Liu, Chinese Fitness, Qi Gong for Healthy and Joyful Living
By my original teacher in Germany, Master at that time but in the meantime he is a Grandmaster. Excellent and easy to understand introduction to the principles of Qi Gong.
Youtube clips: Qingshan Liu shows some of the moves of the “Harmony in 18 figures”. Though he comments in German, it is beautiful to watch his performance.
Some interesting articles by John Munro, an international Qi Gong teacher and expert can be found here: https://www.longwhitecloudqigong.com/what-are-the-benefits-of-qigong/