Purchase a Safari online subscription - many of the books are available on there electronically.
If you're affiliated with a University they may have access to this service, or your public library may as well.
Otherwise, I would suggest you purchase the SAS BaseCertification Guide and work through that instead. I also find it a great desktop reference book.
IMO, 'practicing questions' daily won't help your programming skills, knowing how to do something is important, knowing when you need to actually do said things is the difference between actually understanding what you're doing and is a different skill set learned through experience. Books won't give you that experience. A well laid out course may, but work experience is still vital.
The first SAS Programming course is free, if you haven't completed this yet.
I'll move this to the SAS certification forum and you can review other peoples questions in either SAS Certification/Training/Analytics U for suggestions on learning SAS.