Perhaps you should try some spelling variations:
khanh trach » khanh tra
thuoc khanh » thuoc khang, thuoc thanh, thuc hanh
trach nhiem » trac nghiem
thu nghiem » thuc nghiem, thi nghiem
thu sach » tu sach, thuat sach, thuoc sach
sach thu » sach thue, sach thieu, sach tham
nhiem dc » nghiem de, nghiem do, nhiem va
de hoc » te hoc, du hoc, dien hoc
dc hoc » duc hoc, du hoc, duoc hoc
d hoc » du hoc, ad hoc, y hoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( thu sach thu nghiem ((d hoc) OR (de hoc)) ) or ( thuoc khanh trach nhiem dc hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( thu sach thu nghiem ((d hoc) OR (de hoc)) ) OR ( thuoc khanh trach nhiem dc hoc ))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( thu sach thu nghiem ((d hoc) OR (de hoc)) ) or ( thuoc khanh trach nhiem dc hoc ))*".