Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
ky tang » ky nang, ky dang, kho tang
tang ha » lang ha, tang ma, trung ha
va hanh » van hanh, va thanh, va danh
ha hoi » hoa hoi, ha noi, xa hoi
ve cao » va cao, ve bao, ve co
ve cac » va cac, vien cac
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 cac) or (thu sach)) ky tang ha hoi. hieu ((ve cao) OR (ve cac)) duc va hanh vi cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu cac) OR (thu sach)) ky tang ha hoi. hieu ((ve cao) OR (ve cac)) duc va hanh vi cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu cac) or (thu sach)) ky tang ha hoi. hieu ((ve cao) OR (ve cac)) duc va hanh vi cua vat".
• Adding a wildcard symbol may retrieve word variants: ((tu cac) or (thu sach)) ky tang ha hoi. hieu ((ve cao) OR (ve cac)) duc va hanh vi cua vat*.