Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
cua tre » cua te, cua triet, dua tren
va hanh » van hanh, va thanh, va danh
van cac » van hac, van cau, van bac
su sach » so sach, vu sach
ly hang » ly quang
ly nang » ky nang, ly vang, ly quang
cuu tre » cau tren, cau treo
du va » dau va, tu va, su va

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 ((ly nang) OR (ly hang)) xa hoi. hieu van cac du va hanh vi ((cua tre) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((ly nang) OR (ly hang)) xa hoi. hieu van cac du va hanh vi ((cua tre) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((ly nang) OR (ly hang)) xa hoi. hieu van cac du va hanh vi ((cua tre) or (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: su sach ((ly nang) OR (ly hang)) xa hoi. hieu van cac du va hanh vi ((cua tre) or (cuu tre))*.