Perhaps you should try some spelling variations:
cac thue » cuc thue, cac thu, cach thuc
nang tai » hang tai, tang tai, sang tai
tu sach » thu sach, su sach, tu cach
te sach » toc sach
hieu va » lieu va, hieu qua
thue va » thuc va, thuyet va, thuc vat
va nang » van nang, da nang, cam nang
y nang » ky nang, ly nang, v nang
cuc te » cua te, cuc thue, cuc tieu
5 hoi » o 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) OR (te sach)) y nang ((5 hoi) or (xa hoi)). hieu va cac thue va nang tai cuc te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (te sach)) y nang ((5 hoi) OR (xa hoi)). hieu va cac thue va nang tai cuc te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (te sach)) y nang ((5 hoi) or (xa hoi)). hieu va cac thue va nang tai cuc te".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (te sach)) y nang ((5 hoi) or (xa hoi)). hieu va cac thue va nang tai cuc te*.