Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
dang xay » dang van, van xay
tu sach » thu sach, su sach, te sach
cac toc » cac toi, cac nuoc, cac thoi
doi cua » dai cua, hoi cua
sach ky » sac ky, sach y, sach ty
cac tac » cac bac, cac dac, cac tai
hieu ve » hieu va, hieu van
xay hoi » xa hoi, tay hoi, cay phoi
ky dang » ky nang, ky danh
di cua » dai cua, de cua, do cua

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 dang xay hoi. hieu ve ((cac tac) OR (cac toc)) ban thanh ((di cua) or (doi cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky dang xay hoi. hieu ve ((cac tac) OR (cac toc)) ban thanh ((di cua) OR (doi cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky dang xay hoi. hieu ve ((cac tac) OR (cac toc)) ban thanh ((di cua) or (doi cua)) tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky dang xay hoi. hieu ve ((cac tac) OR (cac toc)) ban thanh ((di cua) or (doi cua)) tre*.