Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
cua viet » ca viet, hoa viet, cua vat
nang ma » tang ma, sang ma, nang cao
hieu va » lieu va, hieu qua
cam tuc » cam xuc, cam tu, nam thuc
tuc van » thuc van, truc van, tuc va
cua tre » cua te, cuu tre, cua triet
cai ky » cac ky, cam ky, sai ky
ma hoi » mai hoi, xa hoi, ma hoa
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: tu ((cai ky) OR (cao ky)) nang ma hoi. hieu va cam tuc van hanh vi ((cua tre) OR (cua viet))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((cai ky) OR (cao ky)) nang ma hoi. hieu va cam tuc van hanh vi ((cua tre) or (cua viet))~".
• Adding a wildcard symbol may retrieve word variants: tu ((cai ky) OR (cao ky)) nang ma hoi. hieu va cam tuc van hanh vi ((cua tre) or (cua viet))*.