Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
tu sach » su sach, te sach, tu cach
vai cua » dai cua, hai cua, lai cua
dan vai » dan va, dan tai, dan vat
cac tuc » cac toc, cac tu, cac tac
hieu va » lieu va, hieu qua
hieu ve » hieu van
dang ma » dang mau, dang mam, dang mat
ky dang » ky nang, ky danh
ma hoi » mai hoi, xa hoi, ma hoa
tuc va » thuc va, truc va, tuc xa
va dan » ca dan, 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) OR (thu sach)) ky dang ma hoi. ((hieu ve) or (hieu va)) cac tuc va dan vai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) ky dang ma hoi. ((hieu ve) OR (hieu va)) cac tuc va dan vai cua te*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (thu sach)) ky dang ma hoi. ((hieu ve) or (hieu va)) cac tuc va dan vai cua te*".