Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
cau tren » cu tren, dau tren, ca tren
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
ve pham » vi pham, v pham, ve phan
va hanh » van hanh, va thanh, va danh
cua te » cua tu
o hoi » co hoi, o hoc, o hoa
o hai » co hai, so hai, o lai

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuoc sach ky nang ((o hoi) or (o hai)). hieu ve pham duc va hanh vi ((cua te) or (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc sach ky nang ((o hoi) OR (o hai)). hieu ve pham duc va hanh vi ((cua te) OR (cau tren)).
• Adding a wildcard symbol may retrieve word variants: thuoc sach ky nang ((o hoi) or (o hai)). hieu ve pham duc va hanh vi ((cua te) or (cau tren))*.