Perhaps you should try some spelling variations:
mai khoi » mai khoa, tai khoa, cac khoi
tu sach » thu sach, su sach, te sach
vai cua » dai cua, hai cua, lai cua
dao vai » dao van, dao va, dao bai
cac tuc » cac toc, cac tu, cac tac
hieu va » lieu va, hieu qua
hieu ve » hieu van
sach ky » sac ky, sach y, sach ty
mai hoi » dai hoi, lai hoi, mai doi
ky sang » ky nang, ky dang, ky tang
tuc va » thuc va, truc va, tuc xa
va dao » ca dao
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 ((mai hoi) OR (mai khoi)). ((hieu ve) or (hieu va)) cac tuc va dao vai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky sang ((mai hoi) OR (mai khoi)). ((hieu ve) OR (hieu va)) cac tuc va dao vai cua te*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky sang ((mai hoi) OR (mai khoi)). ((hieu ve) or (hieu va)) cac tuc va dao vai cua te*".