Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
hieu ha » hieu hoa, hieu va, hieu ca
nam qua » nam quan, nam cua, nam mua
va hanh » van hanh, va thanh, va danh
hanh di » hanh vi, hanh de, hang di
cua tre » cua te, cuu tre, dua tren
qua va » quan va, qua van, vua va
x hoi » o hoi, x ho, 5 hoi

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 nang ((x hoi) or (xa hoi)). hieu ha nam qua va hanh di ((cua tre) OR (cua triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((x hoi) OR (xa hoi)). hieu ha nam qua va hanh di ((cua tre) OR (cua triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((x hoi) or (xa hoi)). hieu ha nam qua va hanh di ((cua tre) OR (cua triet))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((x hoi) or (xa hoi)). hieu ha nam qua va hanh di ((cua tre) OR (cua triet))*.