Perhaps you should try some spelling variations:
trinh nghien » trinh nghe, kinh nghiem, trinh thiet
hanh trinh » hanh chinh
nghien li » nguyen li, nghiem vi, nghiep ly
tranh thi » tranh thai, tran thi, trinh thi
tu hanh » du hanh, lu hanh, thuc hanh
tu canh » thu canh, tu chanh, tu can
thi dia » thi dua, thi da, thi diu
dia hoc » dia oc, dich 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: (( tu hanh trinh nghien li hoc ) or ( tu canh tranh thi dia hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu hanh trinh nghien li hoc ) OR ( tu canh tranh thi dia hoc )).
• Adding a wildcard symbol may retrieve word variants: (( tu hanh trinh nghien li hoc ) or ( tu canh tranh thi dia hoc ))*.