Perhaps you should try some spelling variations:
thanh lap » thanh san, phan lap, thanh hai
hac quoc » han quoc, hoc quoc, cac quoc
su triet » su viet, su tien, ve triet
va triet » va thiet, va trien, ve triet
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
va hac » van hac, va khac, va cac
x hoi » xa hoi, x ho, 5 hoi
o hoi » co hoi, o hoc, o hai
gia » giao

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 nang ((x hoi) OR (o hoi)). lieu va hac quoc gia thanh lap ((su triet) or (va triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((x hoi) OR (o hoi)). lieu va hac quoc gia thanh lap ((su triet) OR (va triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((x hoi) OR (o hoi)). lieu va hac quoc gia thanh lap ((su triet) or (va triet))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((x hoi) OR (o hoi)). lieu va hac quoc gia thanh lap ((su triet) or (va triet))*.