Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hanh vai » hanh vi, hanh va, hanh tai
nam thuc » nam thuoc, am thuc, nam thu
hieu van » hieu va, thien van, lieu va
vai cuu » vai cua
xa hanh » xa thanh, xa khanh, va hanh
thuc xa » thuc xay, tuc xa, thuc va
cuu tre » cua tre, cau tren, cau treo
ky tang » ky dang, kho tang, ky trong
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) OR (ky nang)) ma hoi. hieu van nam thuc xa hanh vai cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ((ky tang) OR (ky nang)) ma hoi. hieu van nam thuc xa hanh vai cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) or (toc sach)) ((ky tang) OR (ky nang)) ma hoi. hieu van nam thuc xa hanh vai cuu tre".
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (toc sach)) ((ky tang) OR (ky nang)) ma hoi. hieu van nam thuc xa hanh vai cuu tre*.