Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
hieu van » hieu va, thien van, lieu va
hanh tai » thanh tai, hang tai, han tai
tu sach » thu sach, su sach, te sach
nang ho » nang hoc, nang co, tang ho
van cac » van hac, van cau, van bac
duc ban » duc tan, duc van, dua ban
cua tre » cua te, cuu tre, dua tren
y nang » ky nang, ly nang, v nang
ho hai » hoc hai, pho hai, cho hai

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 y nang ho hai. hieu van cac ((duc ban) or (duc va)) hanh tai ((cua tre) OR (cua triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang ho hai. hieu van cac ((duc ban) OR (duc va)) hanh tai ((cua tre) OR (cua triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang ho hai. hieu van cac ((duc ban) or (duc va)) hanh tai ((cua tre) OR (cua triet))".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang ho hai. hieu van cac ((duc ban) or (duc va)) hanh tai ((cua tre) OR (cua triet))*.