Perhaps you should try some spelling variations:
trinh thiet » trinh viet, trinh thi
chinh nhiet » chinh viet, trinh nhiet, chinh hien
hanh trinh » canh tranh
thiet quoc » thuat quoc, thi quoc, tieu quoc
lu hanh » luu hanh, du hanh, ly hanh
tu hanh » du hanh, thuc hanh, thi hanh
du hoc » tu hoc, duoc hoc
d hoc » ad hoc, de hoc, y hoc

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 chinh nhiet ((d hoc) or (du hoc)) ) or ( tu hanh trinh thiet quoc hoi ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( lu hanh chinh nhiet ((d hoc) OR (du hoc)) ) OR ( tu hanh trinh thiet quoc hoi )).
• Adding a wildcard symbol may retrieve word variants: (( lu hanh chinh nhiet ((d hoc) or (du hoc)) ) or ( tu hanh trinh thiet quoc hoi ))*.