Perhaps you should try some spelling variations:
dang hanh » dang thanh, ban hanh, dang van
thuc dang » thuoc dang, thuc dan, thuc dung
nang mai » nang ma, nang tai, lang mai
hieu van » thien van, lieu va
nam thuc » nam thuoc, am thuc, nam thu
tu sach » thu sach, su sach, te sach
sach ho » sach hoi, sach ha, sach lo
ho nang » thi nang, kha nang, cao nang
mai hoi » mai khoi, dai hoi, lai hoi
hieu va » lieu va, hieu qua
vi cua » vai cua, di cua

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 ho nang mai hoi. ((((hieu van) OR (hieu ve))) or (hieu va)) nam thuc dang hanh vi cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ho nang mai hoi. ((((hieu van) OR (hieu ve))) OR (hieu va)) nam thuc dang hanh vi cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ho nang mai hoi. ((((hieu van) OR (hieu ve))) or (hieu va)) nam thuc dang hanh vi cua vat".
• Adding a wildcard symbol may retrieve word variants: tu sach ho nang mai hoi. ((((hieu van) OR (hieu ve))) or (hieu va)) nam thuc dang hanh vi cua vat*.