Perhaps you should try some spelling variations:
"su canh tranh nghiem duoc hoc" » "su canh trac nghiem duoc hoc", "su canh trach nhiem duoc hoc", "su canh trinh nghien duoc hoc", "su canh tranh nghiem thuoc hoc", "su canh tranh nghe duoc hoc", "su canh tranh nghiem quoc hoi", "suc canh tranh nghiem duoc hoc", "su can tranh nghiem duoc hoc", "su anh tranh nghiem duoc hoc"
"su sach va nghien tu hoc" » "su sach va nghiep tu hoc", "su sach va nghien cuu hoc", "su sach va nghiep vu hoc", "so sach va nghien tu hoc", "vu sach va nghien tu hoc", "su sach xa nghien tu hoc", "su sach ha nghien tu hoc", "su sach dao nghien tu hoc", "su sach va nghien te hoc"

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("su sach va nghien tu hoc") or ("su canh tranh nghiem duoc hoc"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("su sach va nghien tu hoc") OR ("su canh tranh nghiem duoc hoc")).
• Removing quotes may allow a broader search: (( su sach va nghien tu hoc ) or ( su canh tranh nghiem duoc hoc )).
• Adding a wildcard symbol may retrieve word variants: (("su sach va nghien tu hoc") or ("su canh tranh nghiem duoc hoc"))*.