Perhaps you should try some spelling variations:
hieu quan » lieu quan, thien quan, lien quan
hoc sach » hoc sinh, hoc cac, hoc anh
vat hanh » vat thanh, van hanh, va hanh
cam thuc » am thuc, nam thuc, cam thu
hanh va » hang va, hanh vi
chu tre » cho tre, chu tri, cuu tre
sach ty » sach y, sach tu, sach thu
hieu ve » hieu va, hieu van
tang ma » mang may, tang van
ty tang » tay tang, ty xang, ty hang
ma hoi » mai hoi, xa hoi, ma hoa
va chu » va che, va cau, va chi

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc sach ty tang ma hoi. ((((hieu ve) or (hieu qua))) or (hieu quan)) cam thuc vat hanh va chu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach ty tang ma hoi. ((((hieu ve) OR (hieu qua))) OR (hieu quan)) cam thuc vat hanh va chu tre.
• Adding a wildcard symbol may retrieve word variants: hoc sach ty tang ma hoi. ((((hieu ve) or (hieu qua))) or (hieu quan)) cam thuc vat hanh va chu tre*.