Perhaps you should try some spelling variations:
chanh tranh » canh tranh, hanh trinh, nhanh thanh
tranh nhiem » trach nhiem, trinh nhiet
trinh thiet » trinh thi
trinh viet » ninh viet, trinh vat
tu chanh » tu hanh, tu thanh, tu chung
duoc hoc » quoc hoi
nhiem d » nghiem d, nghiem de, nghiem do
tu sach » thu sach, su sach, te sach
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 chanh tranh nhiem d hoc ) OR ( tu sach ((trinh thiet) OR (trinh viet)) duoc hoc ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tu chanh tranh nhiem d hoc ) or ( tu sach ((trinh thiet) OR (trinh viet)) duoc hoc ))~".
• Adding a wildcard symbol may retrieve word variants: (( tu chanh tranh nhiem d hoc ) or ( tu sach ((trinh thiet) OR (trinh viet)) duoc hoc ))*.