Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
tinh doi » trinh doc, trinh do, tinh hoc
va triet » va trien, ve triet, cua triet
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
va tinh » may tinh
ve cac » va cac, vien cac
x hoi » xa hoi, x ho, 5 hoi
o hoi » co hoi, o hoc, o hai
thiet » thieu

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