Perhaps you should try some spelling variations:
te sach » toc sach
tu nong » tu cong, tu tong, tu tuong
hieu va » lieu va, hieu qua
mo thuc » mot thuc, do thuc, co thuc
thuc va » thuc vat, thuc dan, thuc day
va hanh » van hanh, va thanh, va danh
vai cua » hai cua, lai cua, bai cua
va mo » va mot, va moi, vi mo

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ((tu nong) OR (tu dong)) xa hoi. hieu va mo thuc va hanh ((vai cua) or (dai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((tu nong) OR (tu dong)) xa hoi. hieu va mo thuc va hanh ((vai cua) OR (dai cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ((tu nong) OR (tu dong)) xa hoi. hieu va mo thuc va hanh ((vai cua) or (dai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: te sach ((tu nong) OR (tu dong)) xa hoi. hieu va mo thuc va hanh ((vai cua) or (dai cua)) tre*.