Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
thanh do » thanh de, thanh pho, thanh hoa
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
van hoe » van hoc, van hieu, van hien
hieu va » lieu va, hieu qua
do cua » doi cua, co cua, de cua
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 nang ((van hoa) or (van hoe)). hieu va ((am hoc) OR (ad hoc)) ban thanh do cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((van hoa) OR (van hoe)). hieu va ((am hoc) OR (ad hoc)) ban thanh do cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((van hoa) or (van hoe)). hieu va ((am hoc) OR (ad hoc)) ban thanh do cua te".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((van hoa) or (van hoe)). hieu va ((am hoc) OR (ad hoc)) ban thanh do cua te*.