Perhaps you should try some spelling variations:
trinh nghien » trinh nghe, kinh nghiem, trinh thiet
trai nghiem » trac nghiem, thi nghiem
khach trai » khac trai, khanh tra, kham trai
nghien su » nghiem su, nghien cuu, nghiep sua
nghiem de » nghiem d, nghiem te, nghiem ve
su khach » vu khach, su khac, cua khach
su sach » vu sach
so sach » so sanh, bo sach, co sach
su hoc » tu hoc, du hoc, so hoc
de hoc » te hoc, du hoc, 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: (( ((su sach) OR (so sach)) trinh nghien su hoc ) or ( su khach trai nghiem de hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( ((su sach) OR (so sach)) trinh nghien su hoc ) OR ( su khach trai nghiem de hoc ))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( ((su sach) OR (so sach)) trinh nghien su hoc ) or ( su khach trai nghiem de hoc ))*".