Perhaps you should try some spelling variations:
thanh tai » thanh hai, thanh toan, doanh tai
thuc dan » thuc hanh, hoc dan, thuc vat
so sach » so sanh, bo sach, co sach
tai cua » thai cua, tai cuc, tri cua
truc va » thuc va, thuc vat, trung va
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va, hieu van
su dang » su dung
tu dang » thu dang, tu dong, vu dang
ve nam » he nam, va nam, le nam

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ((tu dang) OR (su dang)) xa hoi. hieu ve nam ((truc va) or (thuc dan)) thanh tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ((tu dang) OR (su dang)) xa hoi. hieu ve nam ((truc va) OR (thuc dan)) thanh tai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ((tu dang) OR (su dang)) xa hoi. hieu ve nam ((truc va) or (thuc dan)) thanh tai cua tre".
• Adding a wildcard symbol may retrieve word variants: so sach ((tu dang) OR (su dang)) xa hoi. hieu ve nam ((truc va) or (thuc dan)) thanh tai cua tre*.