Perhaps you should try some spelling variations:
van thanh » ban thanh
thu sach » tu sach, thuat sach, thuoc sach
than cua » nhan cua, thai cua, ban cua
van tuan » van quan, van ban, anh tuan
vien cac » vien bach, vien dai, vien da
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cuu tre, cua triet
ve cac » va cac
nang o » nang co, nang ho, nang ro
o hoi » co hoi, o hoc, o hai

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ky nang o hoi. hieu ((ve cac) or (vien cac)) xuc ((van thanh) OR (van tuan)) than cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang o hoi. hieu ((ve cac) OR (vien cac)) xuc ((van thanh) OR (van tuan)) than cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky nang o hoi. hieu ((ve cac) or (vien cac)) xuc ((van thanh) OR (van tuan)) than cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sach ky nang o hoi. hieu ((ve cac) or (vien cac)) xuc ((van thanh) OR (van tuan)) than cua tre*.