Perhaps you should try some spelling variations:
hieu sau » hieu su, hieu suat, tieu su
hanh tai » thanh tai, hang tai, han tai
tai cua » thai cua, tai cuc, tri cua
va hanh » van hanh, va thanh, va danh
cham lo » cham o, cam lo, cham soc
cua tre » cua te, cuu tre, cua triet
sach ty » sach tu, sach thu, xach tay
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa
lo va » lo van, lao va, ly va

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuoc ((sach ty) or (sach y)) nang ma hoi. ((hieu sau) or (hieu qua)) cham lo va hanh tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc ((sach ty) OR (sach y)) nang ma hoi. ((hieu sau) OR (hieu qua)) cham lo va hanh tai cua tre.
• Adding a wildcard symbol may retrieve word variants: thuoc ((sach ty) or (sach y)) nang ma hoi. ((hieu sau) or (hieu qua)) cham lo va hanh tai cua tre*.