Perhaps you should try some spelling variations:
doanh ca » doanh cua, doanh cao, doanh va
thi hang » thi hanh, thi nang, thi hong
tu sach » thu sach, su sach, te sach
hieu ve » hieu va, hieu van
cua tre » cua te, cuu tre, cua triet
ty nang » ky nang, ty xang, ty hang
ca cua » co cua
ve cam » ve cham, ve cac, va cam
lo va » lo van, lao va, le va

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ((ty nang) or (thi hang)) xa hoi. hieu ve cam ((lo va) OR (ly va)) doanh ca cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ty nang) OR (thi hang)) xa hoi. hieu ve cam ((lo va) OR (ly va)) doanh ca cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ty nang) or (thi hang)) xa hoi. hieu ve cam ((lo va) OR (ly va)) doanh ca cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ty nang) or (thi hang)) xa hoi. hieu ve cam ((lo va) OR (ly va)) doanh ca cua tre*.