Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
sach ky » sach y, sach ty, sach kem
dai hoi » dai hoc, dai hai, dai moi
van cac » van hac, van cau, van bac
va hanh » van hanh, va thanh, va danh
sac ky » cac ky, sai ky
ma hoi » mai hoi, xa hoi, ma hoa
dan va » doan va, dan ca, ban va
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 ky) or (sac ky)) nang ((ma hoi) or (dai hoi)). hieu van cac dan va hanh vi cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sac ky)) nang ((ma hoi) OR (dai hoi)). hieu van cac dan va hanh vi cua vat.
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (sac ky)) nang ((ma hoi) or (dai hoi)). hieu van cac dan va hanh vi cua vat*.