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

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