Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
thanh tai » thanh hai, thanh toan, doanh tai
hieu van » hieu va, thien van, lieu va
cau tren » cu tren, dau tren, ca tren
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cuu tre, cua triet
me hoi » le 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 ky nang ((me hoi) or (ma hoa)). hieu van nam cua ban thanh tai ((cua tre) or (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((me hoi) OR (ma hoa)). hieu van nam cua ban thanh tai ((cua tre) OR (cau tren)).
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((me hoi) or (ma hoa)). hieu van nam cua ban thanh tai ((cua tre) or (cau tren))*.