Good overview & place to get started learning about the concept.
Another good introductory piece.
Provides helpful information for first-time instructors of Hyflex courses based on the decisions approved by the faculty and the experiences of instructors who have previously taught Hyflex courses.
Analyzes a research article about HyFlex, pulling out lessons learned to consider when trying the model yourself.
Hybrid-Flexible Course Design, ed. Brian J. Beatty (2019)
This free e-book covers why to use a HyFlex approach, how to implement it, and case studies.