Perhaps you should try some spelling variations:
trinh nghien » trinh nghe, kinh nghiem, trinh thiet
kinh nghien » kinh nghiem, kinh hien
canh trinh » canh tranh, hanh trinh, canh tinh
tu canh » thu canh, tu chanh, tu can
so sach » so sanh, bo sach, co sach
de hoc » te hoc, dien hoc
du hoc » tu hoc, duoc hoc
o hoc » co hoc, mo hoc, so hoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tu canh trinh nghien ((de hoc) or (du hoc)) ) or ( so sach kinh nghien ((o hoc) or (y hoc)) ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu canh trinh nghien ((de hoc) OR (du hoc)) ) OR ( so sach kinh nghien ((o hoc) OR (y hoc)) )).
• Adding a wildcard symbol may retrieve word variants: (( tu canh trinh nghien ((de hoc) or (du hoc)) ) or ( so sach kinh nghien ((o hoc) or (y hoc)) ))*.