Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
dang xay » dang van, van xay
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam thu
sach ky » sac ky, sach y, sach ty
ky dang » ky nang, ky danh
xay hoi » xa hoi, tay hoi, cay phoi
thuc va » thuc vat, thuc dan, thuc day
dan tai » van tai, dan thi, han tai
cua tre » cua te, cua triet, dua tren
cuu tre » cau tren, cau treo
va dan » ca dan, va dao, va dau

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 dang xay hoi. hieu van nam thuc va dan tai ((cua tre) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky dang xay hoi. hieu van nam thuc va dan tai ((cua tre) OR (cuu tre)).
• Adding a wildcard symbol may retrieve word variants: toc sach ky dang xay hoi. hieu van nam thuc va dan tai ((cua tre) or (cuu tre))*.