Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
hieu hien » bieu hien, dieu hien, chieu chien
dinh vai » dinh van, dinh vi, dinh va
van dinh » van minh, van dich, va dinh
hien cac » thien cac, vien cac, hieu cac
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
cua tre » cua te, cuu tre, dua tren
su sach » so sach, vu sach
ma hoi » mai hoi, ma hoa, me hoi
cac lo » cac lop, cac co, cac bo
lo van » le van, vo van, so van

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 ty nang ((ma hoi) OR (xa hoi)). hieu hien cac lo van dinh vai ((cua tre) or (cua triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty nang ((ma hoi) OR (xa hoi)). hieu hien cac lo van dinh vai ((cua tre) OR (cua triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty nang ((ma hoi) OR (xa hoi)). hieu hien cac lo van dinh vai ((cua tre) or (cua triet))".
• Adding a wildcard symbol may retrieve word variants: su sach ty nang ((ma hoi) OR (xa hoi)). hieu hien cac lo van dinh vai ((cua tre) or (cua triet))*.