Perhaps you should try some spelling variations:
dan hanh » dang hanh, dan khanh, dan thanh
tu sach » thu sach, su sach, te sach
ha nang » kha nang, hoa nang, ha tang
da nang » cam nang, kha nang, cao nang
mai hoi » mai khoi, dai hoi, lai hoi
hieu va » hieu qua
thu dan » thuc dan, thu dang, thu ban
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 ((ha nang) OR (da nang)) mai hoi. ((lieu va) or (hieu va)) nam thu dan hanh vi cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ha nang) OR (da nang)) mai hoi. ((lieu va) OR (hieu va)) nam thu dan hanh vi cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ha nang) OR (da nang)) mai hoi. ((lieu va) or (hieu va)) nam thu dan hanh vi cua vat".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ha nang) OR (da nang)) mai hoi. ((lieu va) or (hieu va)) nam thu dan hanh vi cua vat*.