Perhaps you should try some spelling variations:
dan thanh » dang thanh, danh thanh, ban thanh
doc sach » hoc sach, toc sach, nuoc sach
thuc dan » thuc hanh, hoc dan, thuc vat
van hoi » van hoa, van hoc, van loi
van hoe » van hoa, van hoc, van hieu
hieu ve » hieu va, hieu van
vai cua » hai cua, lai cua, bai cua
sach o » sach lo, sac o, sach y
o dang » xo dang, do dang, so dang
ve am » va am

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc sach o dang ((van hoi) or (van hoe)). hieu ve am thuc dan thanh ((vai cua) or (dai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach o dang ((van hoi) OR (van hoe)). hieu ve am thuc dan thanh ((vai cua) OR (dai cua)) tre.
• Adding a wildcard symbol may retrieve word variants: doc sach o dang ((van hoi) or (van hoe)). hieu ve am thuc dan thanh ((vai cua) or (dai cua)) tre*.