Perhaps you should try some spelling variations:
cao tang » cao dang
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
va hanh » van hanh, va thanh, va danh
cam loc » cam lo
van cam » van nam, van lam, van cau
ky lang » ky nang, ky dang, ky tang
cua tre » cua te, cuu tre, cua triet
loc va » hoc va, luc va
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 ((ky lang) or (((kho tang) OR (cao tang)))) xa hoi. hieu van cam loc va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((ky lang) OR (((kho tang) OR (cao tang)))) xa hoi. hieu van cam loc va hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((ky lang) or (((kho tang) OR (cao tang)))) xa hoi. hieu van cam loc va hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ((ky lang) or (((kho tang) OR (cao tang)))) xa hoi. hieu van cam loc va hanh vi cua tre*.