Perhaps you should try some spelling variations:
"so canh tranh nghe tieng hoc" » "so canh trinh nghe tieng hoc", "so canh anh nghe tieng hoc", "so canh hanh nghe tieng hoc", "so canh tranh nghe thong hoc", "so canh tranh nghe tieng han", "so canh tranh nghe trung hoc", "so canh tranh nghe tien hoa", "so sanh tranh nghe tieng hoc", "bo canh tranh nghe tieng hoc", "so danh tranh nghe tieng hoc"
"co sach thi nghiem y hoc" » "co sach thuc nghiem y hoc", "co sach thu nghiem y hoc", "co sach tai nghiem y hoc", "co sach thieu nghiem y hoc", "co sach thi nghiep y hoc", "co sach thi nghiem _ hoc", "co sach thi nghiem d hoc", "bo sach thi nghiem y hoc", "cuon sach thi nghiem y hoc", "hoc sach thi nghiem y 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 canh tranh nghe tieng hoc") or ("co sach thi nghiem y hoc"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("so canh tranh nghe tieng hoc") OR ("co sach thi nghiem y hoc")).
• Removing quotes may allow a broader search: (( so canh tranh nghe tieng hoc ) or ( co sach thi nghiem y hoc )).
• Adding a wildcard symbol may retrieve word variants: (("so canh tranh nghe tieng hoc") or ("co sach thi nghiem y hoc"))*.