Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu sau » hieu su, hieu suat, tieu su
sau pham » san pham, su pham, cau pham
pham day » phap day, pham duy, pham xay
hanh lai » hanh lam, hanh tai, thanh lap
sach ty » sach y, sach tu, sach thu
xang ma » tang ma, nang ma, sang ma
hanh va » hang va, hanh vi
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa

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

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