Perhaps you should try some spelling variations:
dua tren » dung tren
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
ban anh » ban hanh, ban banh, ban danh
cuc ban » cua ban, cac ban, cuu ban
cam cuc » cam xuc, cham cuu, pham cuc
hieu va » lieu va, hieu qua
hieu ve » hieu van
cuu tre » cua tre, cau tren, cau treo
anh di » danh di, xanh di, anh d
x hoi » xa hoi, o hoi, x ho

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 nang x hoi. ((hieu ve) OR (hieu va)) cam cuc ban anh di ((dua tren) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x hoi. ((hieu ve) OR (hieu va)) cam cuc ban anh di ((dua tren) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang x hoi. ((hieu ve) OR (hieu va)) cam cuc ban anh di ((dua tren) or (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x hoi. ((hieu ve) OR (hieu va)) cam cuc ban anh di ((dua tren) or (cuu tre))*.