Perhaps you should try some spelling variations:
thien van » thi van
dang thai » dang thi, dang hai, dang khai
cua triet » cua viet, su triet, va triet
thu sach » tu sach, thuat sach, thuoc sach
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
sach ky » sac ky, sach y, sach ty
van cac » van hac, van cau, van bac
va dang » van dang, va nang, va lang
cua tre » cua te, cuu tre, dua tren
x hoi » xa hoi, x ho, 5 hoi
o hoi » co hoi, o hoc, o hai

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

• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang ((x hoi) OR (o hoi)). thien van cac nuoc va dang thai ((cua tre) OR (cua triet))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky nang ((x hoi) or (o hoi)). thien van cac nuoc va dang thai ((cua tre) OR (cua triet))~".
• Adding a wildcard symbol may retrieve word variants: thu sach ky nang ((x hoi) or (o hoi)). thien van cac nuoc va dang thai ((cua tre) OR (cua triet))*.