Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
van pham » san pham, van phan, van phat
hanh tai » thanh tai, hang tai, han tai
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
mang xa » lang xa, mang may, dang xay
va hanh » van hanh, va thanh, va danh
tai cua » thai cua, tai cuc, tri cua
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ky ((((nang ma) or (mang xa))) or (nang x)) hoi. hieu van pham duc va hanh tai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky ((((nang ma) OR (mang xa))) OR (nang x)) hoi. hieu van pham duc va hanh tai cua te.
• Adding a wildcard symbol may retrieve word variants: toc sach ky ((((nang ma) or (mang xa))) or (nang x)) hoi. hieu van pham duc va hanh tai cua te*.