Perhaps you should try some spelling variations:
hieu quan » hieu qua, lieu quan, thien quan
va trien » va truyen, va thiet, va tuyen
van hanh » van thanh, ban hanh, van anh
dang xay » dang van, van xay
va triet » va thiet, ve triet, cua triet
quan cau » quang cao, toan cau, quan ha
hanh hai » thanh hai, nhanh hai, hang hai
so sach » so sanh, bo sach, co sach
tuc van » thuc van, truc van, tuc va
sach ky » sac ky, sach y, sach ty
xay hoi » xa hoi, tay hoi, cay phoi
ky dang » ky nang, ky danh
cau tuc » cau truc, cau tu, cau luc

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: so sach ky dang xay hoi. hieu quan cau tuc van hanh hai ((va triet) OR (va trien))~.
• Adding a wildcard symbol may retrieve word variants: so sach ky dang xay hoi. hieu quan cau tuc van hanh hai ((va triet) or (va trien))*.