Perhaps you should try some spelling variations:
hieu sau » hieu suat, tieu su, hieu va
cham duc » pham duc, cham soc, pham duy
va chua » vua chua, ca chua, va chu
tinh va » tich va, trinh van, trinh vat
va tinh » may tinh
chua te » cua te, chua tu, chua xe
sach tu » sach thu, cach tu, sach uu
hieu su » tieu su, hieu so, hieu suat
nang xa » nang x, lang xa, nang ma
sach ty » sach y, sach thu, xach tay

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

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sach tu) or (sach ty)) nang xa hoi. ((hieu su) OR (hieu sau)) cham duc va tinh va chua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach tu) OR (sach ty)) nang xa hoi. ((hieu su) OR (hieu sau)) cham duc va tinh va chua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach tu) or (sach ty)) nang xa hoi. ((hieu su) OR (hieu sau)) cham duc va tinh va chua te".
• Adding a wildcard symbol may retrieve word variants: su ((sach tu) or (sach ty)) nang xa hoi. ((hieu su) OR (hieu sau)) cham duc va tinh va chua te*.