Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
tu sach » thu sach, su sach, te sach
hanh va » hang va
thuc va » thuc vat, thuc dan, thuc day
sach ty » sach y, sach tu, sach thu
hieu va » lieu va, hieu qua
dai hoi » dai hoc, dai hai, dai moi
mai hoi » mai khoi, lai hoi, mai doi
ty danh » ty doanh, ty anh, ky danh
cu tren » tu tren, dua tren
va nam » van nam, ha nam, va nay

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ty danh ((mai hoi) OR (dai hoi)). hieu va nam thuc va ((hanh vi) or (hanh va)) cu tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty danh ((mai hoi) OR (dai hoi)). hieu va nam thuc va ((hanh vi) OR (hanh va)) cu tren*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty danh ((mai hoi) OR (dai hoi)). hieu va nam thuc va ((hanh vi) or (hanh va)) cu tren*".