Perhaps you should try some spelling variations:
van doanh » toan doanh, van dong, van thanh
thien van » thi van
hieu van » hieu va, lieu va, hieu ve
doanh va » doan va, doanh tai, doanh cua
tu sach » thu sach, su sach, te sach
ty nang » ky nang, ty hang, ly nang
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa
cam ky » cao ky, cac ky
ky van » ly van, ty van, ky va
va cua » va chua, via cua, ca 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 ((ty nang) OR (ty xang)) ma hoi. ((hieu van) or (thien van)) cam ky van doanh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ty nang) OR (ty xang)) ma hoi. ((hieu van) OR (thien van)) cam ky van doanh va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ty nang) OR (ty xang)) ma hoi. ((hieu van) or (thien van)) cam ky van doanh va cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ty nang) OR (ty xang)) ma hoi. ((hieu van) or (thien van)) cam ky van doanh va cua tre*.