Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam thu
hanh tai » thanh tai, hang tai, han tai
ky tang » ky nang, ky dang, kho tang
tang ma » mang may, tang van
thuc xa » thuc xay, tuc xa, thuc va
xa hanh » xa thanh, xa khanh, va hanh
tai cuu » tai cuc, tai buu, tai cua
cuu tre » cua tre, cau tren, cau treo
ma hoi » mai hoi, xa hoi, ma hoa

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

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