Perhaps you should try some spelling variations:
kha trinh » qua trinh, ha tinh, tra trinh
thiet yeu » theo yeu
trinh su » trinh tu, trinh san, trinh cau
ton giao » toan giao, so giao, don gian
hoc giao » hoc cao
tu hanh » du hanh, lu hanh, thuc hanh
vu kha » vu kham, vu khac, vu khoa

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

• If you are trying to use Boolean operators, they must be ALL CAPS: (( vu kha trinh su - ton giao ) OR ( tu hanh ((thiet yeu) OR (thiet ke)) - hoc giao ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( vu kha trinh su - ton giao ) or ( tu hanh ((thiet yeu) OR (thiet ke)) - hoc giao ))~".
• Adding a wildcard symbol may retrieve word variants: (( vu kha trinh su - ton giao ) or ( tu hanh ((thiet yeu) OR (thiet ke)) - hoc giao ))*.