Perhaps you should try some spelling variations:
va thanh » gia thanh, ban thanh, le thanh
hieu van » hieu va, thien van, lieu va
so sach » so sanh, bo sach, co sach
sach ky » sac ky, sach y, sach ty
va tinh » may tinh
cam tuc » cam xuc, cam tu, nam thuc
van cam » van nam, van lam, van cau
co hoi » co hoc, co loi
di cua » dai cua, doi cua, de cua
cua te » cua tu
o hoi » o hoc, o hai, o hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ky nang ((o hoi) OR (co hoi)). hieu van cam tuc ((va thanh) or (va tinh)) di cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ky nang ((o hoi) OR (co hoi)). hieu van cam tuc ((va thanh) OR (va tinh)) di cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ky nang ((o hoi) OR (co hoi)). hieu van cam tuc ((va thanh) or (va tinh)) di cua te".
• Adding a wildcard symbol may retrieve word variants: so sach ky nang ((o hoi) OR (co hoi)). hieu van cam tuc ((va thanh) or (va tinh)) di cua te*.