Perhaps you should try some spelling variations:
"bo sach thieu nghiem y hoc" » "bo sach thi nghiem y hoc", "bo sach thu nghiem y hoc", "bo sach thieu nhi y hoc", "bo sach thieu nghiep y hoc", "bo sach thieu nghiem _ hoc", "bo sach thieu nghiem d hoc", "co sach thieu nghiem y hoc", "hoc sach thieu nghiem y hoc"
"so sanh trinh nghien dien hoc" » "so sanh trinh nghe dien hoc", "so sanh kinh nghiem dien hoc", "so sanh trinh thiet dien hoc", "so sanh trinh nghiep dien hoc", "so sanh trinh khien dien hoc", "so hanh trinh nghien dien hoc", "so anh trinh nghien dien hoc", "so sinh trinh nghien dien hoc", "so sanh trinh nghien dien hoa", "so sanh trinh nghien khien hoc", "so sanh trinh nghien tin hoc", "do sanh trinh nghien dien hoc"

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("so sanh trinh nghien dien hoc") or ("bo sach thieu nghiem y hoc"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("so sanh trinh nghien dien hoc") OR ("bo sach thieu nghiem y hoc")).
• Removing quotes may allow a broader search: (( so sanh trinh nghien dien hoc ) or ( bo sach thieu nghiem y hoc )).
• Adding a wildcard symbol may retrieve word variants: (("so sanh trinh nghien dien hoc") or ("bo sach thieu nghiem y hoc"))*.