Perhaps you should try some spelling variations:
cham doc » cham soc, chat doc, chau doc
cuu tre » cau tren, cau treo
cua tre » cua te, cua triet, dua tren
hieu va » lieu va, hieu qua
va cham » va chat, va tham
tang ma » mang may, tang van
tang xa » trang xa, lang xa, tang ha
ban ky » van ky, dan ky
doc va » duoc va, hoc va, duc va
va dan » ca dan, va dao, va dau
dan vi » doan vi, don vi, dan va
tu ban » thu ban, te ban

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu ban ky ((tang xa) OR (tang ma)) hoi. hieu va cham doc va dan vi ((cua tre) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ban ky ((tang xa) OR (tang ma)) hoi. hieu va cham doc va dan vi ((cua tre) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ban ky ((tang xa) OR (tang ma)) hoi. hieu va cham doc va dan vi ((cua tre) or (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: tu ban ky ((tang xa) OR (tang ma)) hoi. hieu va cham doc va dan vi ((cua tre) or (cuu tre))*.