Perhaps you should try some spelling variations:
dang xay » dang van, van xay
hanh vai » hanh vi, hanh va, hanh tai
van hanh » van thanh, ban hanh, van anh
vai cua » dai cua, hai cua, lai cua
duc van » duc va, duc tan, duc manh
cac duc » cac du, cao duc, cac dac
hieu va » lieu va, hieu qua
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
sach tu » sach thu, cach tu, sach ty
cua tre » cua te, cuu tre, cua triet

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) or (sach tu)) ((nang ma) or (dang xay)) hoi. hieu va cac duc van hanh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sach tu)) ((nang ma) OR (dang xay)) hoi. hieu va cac duc van hanh vai cua tre.
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (sach tu)) ((nang ma) or (dang xay)) hoi. hieu va cac duc van hanh vai cua tre*.