Perhaps you should try some spelling variations:
cham dua » chay dua, cham giua, pham duc
dang xay » van xay
su triet » su tien, ve triet
ban hanh » ban hang
dang van » hoang van, hang va
tu dang » thu dang, tu dong, su dang
dua ban » dia ban, cua ban, qua ban
hieu va » lieu va, hieu qua
va cham » va chat, va tham
dang ky » dang y, dan ky, dong ky
su viet » so viet

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu dang ky ((dang xay) or (dang van)) hoi. hieu va cham dua ban hanh vi ((su triet) OR (su viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu dang ky ((dang xay) OR (dang van)) hoi. hieu va cham dua ban hanh vi ((su triet) OR (su viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu dang ky ((dang xay) or (dang van)) hoi. hieu va cham dua ban hanh vi ((su triet) OR (su viet))".
• Adding a wildcard symbol may retrieve word variants: tu dang ky ((dang xay) or (dang van)) hoi. hieu va cham dua ban hanh vi ((su triet) OR (su viet))*.