Perhaps you should try some spelling variations:
tranh nghiep » trinh nghien, trac nghiem, trinh nghe
trach nhiem » trac nghiem
sach trach » sach tranh, sach truc, sat trach
nhiem van » nghiem van, nhiem va, nghiem ban
te sach » toc sach
su sach » so sach, vu sach
van hoc » van hoa
du hoc » tu hoc, duoc 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: (( te sach ((tranh nghiep) OR (doanh nghiep)) du hoc ) OR ( su sach trach nhiem van hoc ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( te sach ((tranh nghiep) OR (doanh nghiep)) du hoc ) or ( su sach trach nhiem van hoc ))~".
• Adding a wildcard symbol may retrieve word variants: (( te sach ((tranh nghiep) OR (doanh nghiep)) du hoc ) or ( su sach trach nhiem van hoc ))*.