Perhaps you should try some spelling variations:
cham thuc » nham thuc, pham thuc, tham thuc
toc sach » hoc sach, doc sach, thuoc sach
vanh tai » van tai, hanh tai, anh tai
vanh dai » van dai, lanh dao, van dao
dang xay » dang van, van xay
tu sach » thu sach, su sach, te sach
thuc va » thuc vat, thuc dan, thuc day
va cham » va chat, va tham
hieu va » lieu va, hieu qua
xay hoi » xa hoi, tay hoi, cay phoi
ky dang » ky nang, ky danh
cua tre » cua te, cuu tre, cua triet

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