Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
vat cua » mat cua, bat cua, dat cua
dan vat » dang vat, van vat, dan va
cac tuc » cac toc, cac tu, cac tac
hieu va » lieu va, hieu qua
sach ky » sac ky, sach y, sach ty
hieu ve » hieu van
tay hoi » tay ho, tay thai
tao hoi » tao khoi, tao boi, thao hoc
ky sang » ky nang, ky dang, ky tang
tuc va » thuc va, truc va, tuc xa
va dan » ca dan, va dao, va dau
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 ((tao hoi) OR (tay hoi)). ((hieu ve) or (hieu va)) cac tuc va dan vat cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky sang ((tao hoi) OR (tay hoi)). ((hieu ve) OR (hieu va)) cac tuc va dan vat cua tu*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky sang ((tao hoi) OR (tay hoi)). ((hieu ve) or (hieu va)) cac tuc va dan vat cua tu*".