Perhaps you should try some spelling variations:
doanh vi » doanh va, doan vi, doanh vien
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
cuu ban » cuu van, cuu san, cuu nang
cua tre » cua te, cuu tre, cua triet
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang
ve cac » va cac, vien cac
ve cam » ve cham, va cam, ve cai
vi cua » vai cua, di cua

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 ky lang xa hoi. hieu ((ve cam) or (ve cac)) ((cuu ban) OR (cua ban)) doanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky lang xa hoi. hieu ((ve cam) OR (ve cac)) ((cuu ban) OR (cua ban)) doanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky lang xa hoi. hieu ((ve cam) or (ve cac)) ((cuu ban) OR (cua ban)) doanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky lang xa hoi. hieu ((ve cam) or (ve cac)) ((cuu ban) OR (cua ban)) doanh vi cua tre*.