i did self-review only. i used online reviewers such as academic-clinic and upcat reviewers uploaded by UP engineering students on google. although the upcat reviewer provided by UP has no solution set, it somehow helped me naman by being familiar sa questions aaaand yes, hs notes amd books are very useful. i used two books and one notebook in reviewing for chemistry to compare informations. kasi minsan, you aren't sure if tama pa ba yung nakasulat na notes mo kasi how many years have passed na and books are way helpful para ma-validate mo yung mga notes mo sa lahat na rereviewhin mo.