Perhaps you should try some spelling variations:
tu tieng » luc tieng, tu tuong, tu trong
van hanh » van thanh, ban hanh, van anh
su hien » su kien, su tien, thu hien
hanh ve » hanh vi, hanh va, hanh kem
luc van » luoc van, luu van, duc van
sach va » sach xa, sach ha, sach dao
te sach » toc sach
hieu va » lieu va, hieu qua
va nang » van nang, da nang, cam nang
co luc » coc luc, co luy
o hoi » co hoi, o hoc, o hai
x hoi » xa hoi, x ho, 5 hoi
va co » vo co

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach va nang ((x hoi) OR (o hoi)). hieu va co luc van hanh ve ((su hien) or (tu tieng))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach va nang ((x hoi) OR (o hoi)). hieu va co luc van hanh ve ((su hien) OR (tu tieng)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach va nang ((x hoi) OR (o hoi)). hieu va co luc van hanh ve ((su hien) or (tu tieng))".
• Adding a wildcard symbol may retrieve word variants: te sach va nang ((x hoi) OR (o hoi)). hieu va co luc van hanh ve ((su hien) or (tu tieng))*.