Perhaps you should try some spelling variations:
xach tay » canh tay
hieu van » hieu va, thien van, lieu va
sach thu » sach thue, sach thieu, sach tham
thuc va » thuc vat, thuc dan, thuc day
cua tre » cua te, cuu tre, cua triet
ha hoi » hoa hoi, xa hoi, va hoi
van am » van nam, van lam, van dam
va dan » ca dan, va dao, va dau
dan va » doan va, dan ca, ban va
va cua » va chua, via cua, ca cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc ((xach tay) or (sach thu)) long ((ha hoi) OR (ha noi)). hieu van am thuc va dan va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc ((xach tay) OR (sach thu)) long ((ha hoi) OR (ha noi)). hieu van am thuc va dan va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc ((xach tay) or (sach thu)) long ((ha hoi) OR (ha noi)). hieu van am thuc va dan va cua tre".
• Adding a wildcard symbol may retrieve word variants: toc ((xach tay) or (sach thu)) long ((ha hoi) OR (ha noi)). hieu van am thuc va dan va cua tre*.