Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
ba trung » tai trung, nam trung, do trung
nam truc » nam truoc, nam thuc, nam trung
su sach » so sach, vu sach
sach lo » sach dao, sach doi, sach hoi
cua tre » cua te, cuu tre, cua triet
nang xa » nang x, lang xa, mang xa
nang ma » tang ma, sang ma, nang cao
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: su sach lo ((nang xa) or (nang ma)) hoi. lieu va ((nam truc) or (ba trung)) van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach lo ((nang xa) OR (nang ma)) hoi. lieu va ((nam truc) OR (ba trung)) van hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: su sach lo ((nang xa) or (nang ma)) hoi. lieu va ((nam truc) or (ba trung)) van hanh vi cua tre*.