This is the program I started recently. It’s not exclusively on core or hips, but there’s plenty of that and seems to be a huge focus on hip flexibility and strengthening so far. Knee raises (hip flexors to combat imbalance with extensors) and internal and external hip rotations. Working muscles I didn’t know I had! He has mobility drills to go along with every exercise.
I absolutely have no expertise in this area but I'd suggest google scholar because you know I'm a Ph.D. 😄. However, well-known websites like men's/women's health tend to work for me. Also, if you could afford personal trainers/nutritionists are the best.