Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
thi nghiem » thuc nghiem
tam nghien » lam nghiep, va nghien
nghiem de » nghiem d, nghiem te, nghiem ve
nghien de » nghiep ke, nghiem d, nghiem te
cach thi » cach thoi, cac thi, cach thien
thu sach » tu sach, thuoc sach, thu hoach
tu cach » tu cac
de hoc » te hoc, du hoc, dien hoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tu cach thi nghiem de hoc ) or ( ((thu sach) or (thuat sach)) tam nghien de hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu cach thi nghiem de hoc ) OR ( ((thu sach) OR (thuat sach)) tam nghien de hoc )).
• Adding a wildcard symbol may retrieve word variants: (( tu cach thi nghiem de hoc ) or ( ((thu sach) or (thuat sach)) tam nghien de hoc ))*.