Perhaps you should try some spelling variations:
khao nghiem » khao nghiep
trach nhiem » trac nghiem
sach trach » sach tranh, sach truc, sat trach
nha nghiem » nha nghien, thi nghiem, thu nghiem
nhiem tu » nhiem thuc, nhiem huu, nghiem su
thu sach » tu sach, thuat sach, thuoc sach
te sach » toc sach
tu hoc » te hoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( te sach trach nhiem tu hoc ) or ( thu sach ((nha nghiem) or (khao nghiem)) dai hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( te sach trach nhiem tu hoc ) OR ( thu sach ((nha nghiem) OR (khao nghiem)) dai hoc )).
• Adding a wildcard symbol may retrieve word variants: (( te sach trach nhiem tu hoc ) or ( thu sach ((nha nghiem) or (khao nghiem)) dai hoc ))*.