Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
cam thu » nam thu, cac thu, ca thu
thu van » thuc van, thuy van, tu van
ban tai » van tai, han tai, ban thi
cua tre » cua te, cua triet, dua tren
cuu tre » cau tren, cau treo
y nang » ky nang, ly nang, v nang
va cam » va cham, va cac, va cao
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 y nang ((x hoi) or (xa hoi)). hieu va cam thu van ban tai ((cua tre) OR (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang ((x hoi) OR (xa hoi)). hieu va cam thu van ban tai ((cua tre) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang ((x hoi) or (xa hoi)). hieu va cam thu van ban tai ((cua tre) OR (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang ((x hoi) or (xa hoi)). hieu va cam thu van ban tai ((cua tre) OR (cuu tre))*.