Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
van hanh » van thanh, ban hanh, van anh
phan duc » pham duc, phan tu, phan dau
cau tren » cu tren, dau tren, ca tren
hieu ve » hieu va, hieu van
sach ky » sac ky, sach y, sach ty
duc van » duc va, duc tan, duc manh
ve phan » va phan, ke phan, ve phat
co hoi » co hoc, co loi
cua te » cua tu
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 ((co hoi) or (o hai)). hieu ve phan duc van hanh vi ((cua te) or (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc sach ky nang ((co hoi) OR (o hai)). hieu ve phan duc van hanh vi ((cua te) OR (cau tren)).
• Adding a wildcard symbol may retrieve word variants: thuoc sach ky nang ((co hoi) or (o hai)). hieu ve phan duc van hanh vi ((cua te) or (cau tren))*.