Perhaps you should try some spelling variations:
sach tranh » canh tranh
thu nghiem » thuc nghiem, thi nghiem
sach trac » sach truc, sach tham, sach tren
nghiem de » nghiem d, nghiem do, nghiem te
nghiem xu » nghiem su, nghiem xuan, nghiem ngu
sach thu » sach thue, sach thieu, sach tham
te sach » toc sach
de hoc » te hoc, du hoc, dien hoc
xu hoc » tu hoc, du hoc, su 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: (( hoc ((sach trac) OR (sach tranh)) nghiem de hoc ) OR ( te sach thu nghiem xu hoc ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( hoc ((sach trac) OR (sach tranh)) nghiem de hoc ) or ( te sach thu nghiem xu hoc ))~".
• Adding a wildcard symbol may retrieve word variants: (( hoc ((sach trac) OR (sach tranh)) nghiem de hoc ) or ( te sach thu nghiem xu hoc ))*.