Perhaps you should try some spelling variations:
trinh nghien » trinh nghe, kinh nghiem, trinh thiet
hanh trinh » canh tranh, hanh chinh
sach trach » sach tranh, sach truc, sat trach
nghien te » nghiem te, nghiep ke, nghiep tu
nhiem dan » nghiem ban, nghiem van, nghiem dau
nghiem va » nghiep va, nghiep vua, nghiep vu
lu hanh » luu hanh, du hanh, ly hanh
tu sach » thu sach, su sach, te sach

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( lu hanh trinh nghien te hoc ) or ( tu sach trach ((nhiem dan) or (nghiem va)) hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( lu hanh trinh nghien te hoc ) OR ( tu sach trach ((nhiem dan) OR (nghiem va)) hoc )).
• Adding a wildcard symbol may retrieve word variants: (( lu hanh trinh nghien te hoc ) or ( tu sach trach ((nhiem dan) or (nghiem va)) hoc ))*.