Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
duc van » duc va, duc tan, duc manh
van hau » van ha, van hai, van dau
van cam » van nam, van lam, van cau
sach ky » sac ky, sach y, sach ty
tu sach » thu sach, su sach, te sach
nang ma » tang ma, sang ma, nang cao
mang xa » lang xa, mang may, dang xay
cua tre » cua te, cuu tre, cua triet
vi cua » vai cua, di cua

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