Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
bach ky » bac ky
lang ha » long ha
hieu va » lieu va, hieu qua
cam duc » cam xuc, cao duc, pham duc
va dinh » van dinh, va kinh, va tinh
dinh vi » dinh ve, dinh viet, dinh tri
cuu tre » cua tre, cau treo
va cam » va cham, va cac, va cao

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

• If you are trying to use Boolean operators, they must be ALL CAPS: vu bach ky ((nang x) OR (lang ha)) hoi. hieu va cam duc va dinh vi ((cuu tre) OR (cau tren))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu bach ky ((nang x) or (lang ha)) hoi. hieu va cam duc va dinh vi ((cuu tre) OR (cau tren))~".
• Adding a wildcard symbol may retrieve word variants: vu bach ky ((nang x) or (lang ha)) hoi. hieu va cam duc va dinh vi ((cuu tre) OR (cau tren))*.