Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
dap dai » dat dai, tap dai, dap bai
cac tuc » cac toc, cac tu, cac tac
hieu va » lieu va, hieu qua
hieu ve » hieu van
mai hoi » mai khoi, dai hoi, lai hoi
ky tang » ky nang, ky dang, kho tang
ky sang » ky nang, ky dang, duy sang
tuc va » thuc va, truc va, tuc xa
va dap » va dao, va dau
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ((ky sang) OR (ky tang)) mai hoi. ((hieu ve) or (hieu va)) cac tuc va dap dai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ky sang) OR (ky tang)) mai hoi. ((hieu ve) OR (hieu va)) cac tuc va dap dai cua te*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ky sang) OR (ky tang)) mai hoi. ((hieu ve) or (hieu va)) cac tuc va dap dai cua te*".