The book has been written for 15 year olds to adults and is suitable for School and College courses in the US, Canada, UK, Australia, NZ, South Africa, Hong Kong, Singapore etc including IB, GCSE, A Level, Sc & Eng Diplomas, HSC.
There is a great deal of material out there that has merit but I believe that the strengths of Physics Secrets will make it easier and faster for you to understand and recall the subject.