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
nghiem van » nghiem va, nghiem ban, nghiep van
nghien te » nghiem te, nghiep ke, nghiep tu
nhiem dan » nghiem ban, nghiem dau, nghiep dan
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 van)) 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 van)) hoc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( lu hanh trinh nghien te hoc ) or ( tu sach trach ((nhiem dan) OR (nghiem van)) hoc ))".
• Adding a wildcard symbol may retrieve word variants: (( lu hanh trinh nghien te hoc ) or ( tu sach trach ((nhiem dan) OR (nghiem van)) hoc ))*.