Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
van hanh » van thanh, ban hanh, van anh
hieu van » hieu va, thien van, lieu va
sach ty » sach y, sach tu, sach thu
van cac » van hac, van cau, van bac
ty nang » ky nang, ty xang, ty hang
cua tre » cua te, cuu tre, dua tren
te sach » toc sach
co hai » co dai, co hoi, so hai
cac so » cac co, cac bo, cac ho
so van » su van, vo van
o hai » so hai, o lai, _ hai

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ty nang ((co hai) OR (o hai)). hieu van cac so van hanh vi ((cua tre) or (cua triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ty nang ((co hai) OR (o hai)). hieu van cac so van hanh vi ((cua tre) OR (cua triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ty nang ((co hai) OR (o hai)). hieu van cac so van hanh vi ((cua tre) or (cua triet))".
• Adding a wildcard symbol may retrieve word variants: te sach ty nang ((co hai) OR (o hai)). hieu van cac so van hanh vi ((cua tre) or (cua triet))*.