Perhaps you should try some spelling variations:
trinh thiet » trinh viet, trinh thi
tranh nhiem » trach nhiem, trinh nhiet
hanh trinh » hanh chinh
thiet duoc » chet duoc, hiem duoc, thuat duoc
duoc hoc » quoc hoi
tu canh » thu canh, tu chanh, tu can
nhiem d » nghiem d, nghiem de, nhiem va
tu hanh » du hanh, lu hanh, thuc hanh
d hoc » du hoc, ad hoc, de hoc

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: (( tu canh tranh nhiem d hoc ) OR ( tu hanh trinh thiet duoc hoc ))~.
• Adding a wildcard symbol may retrieve word variants: (( tu canh tranh nhiem d hoc ) or ( tu hanh trinh thiet duoc hoc ))*.