Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
danh dai » danh dau, danh di, danh sai
thuc dan » thuc hanh, hoc dan, thuc vat
van pham » san pham, van phan, van phat
sach ky » sac ky, sach ty, sach kem
nang ma » tang ma, sang ma, nang cao
thuc va » thuc vat, thuc day
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa

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

• If you are trying to use Boolean operators, they must be ALL CAPS: toc ((sach ky) OR (sach y)) nang ma hoi. hieu van pham ((thuc va) OR (thuc dan)) danh dai cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc ((sach ky) or (sach y)) nang ma hoi. hieu van pham ((thuc va) OR (thuc dan)) danh dai cua tre~".
• Adding a wildcard symbol may retrieve word variants: toc ((sach ky) or (sach y)) nang ma hoi. hieu van pham ((thuc va) OR (thuc dan)) danh dai cua tre*.