Perhaps you should try some spelling variations:
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
lang xa » lang ha, dang xay, lang van
sach ky » sac ky, sach y, sach kem
sang ma » tang ma, nang ma, sang tao
sach ty » sach y, sach tu, sach thu
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 ty)) ((sang ma) or (lang xa)) 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 ty)) ((sang ma) OR (lang xa)) hoi. hieu va cac duc van hanh vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) OR (sach ty)) ((sang ma) or (lang xa)) hoi. hieu va cac duc van hanh vai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) OR (sach ty)) ((sang ma) or (lang xa)) hoi. hieu va cac duc van hanh vai cua tre*.