Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
hanh tai » thanh tai, hang tai, han tai
hieu ve » hieu va, hieu van
sach ty » sach y, sach tu, sach thu
cua tre » cua te, cuu tre, cua triet
hieu vu » hieu va, hieu su, dieu vu
cao hoi » cau hoi, co hoi, cao hoc
ty nang » ky nang, ty xang, ty hang
cam lo » nam lo, cam ly, cam o
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 nang cao hoi. ((hieu vu) OR (hieu ve)) cam lo va ((hanh tai) or (hanh vi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc sach ty nang cao hoi. ((hieu vu) OR (hieu ve)) cam lo va ((hanh tai) OR (hanh vi)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuoc sach ty nang cao hoi. ((hieu vu) OR (hieu ve)) cam lo va ((hanh tai) or (hanh vi)) cua tre".
• Adding a wildcard symbol may retrieve word variants: thuoc sach ty nang cao hoi. ((hieu vu) OR (hieu ve)) cam lo va ((hanh tai) or (hanh vi)) cua tre*.