Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
va tuyen » va truyen, tac tuyen, ke tuyen
sang mai » sang ma, sang tai, lang mai
hieu luc » hieu luat, hieu qua
danh vi » hanh vi, danh di, danh va
dinh vi » dinh ve, dinh viet, dinh tri
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
mai hoi » mai khoi, dai hoi, lai hoi
ky sang » ky nang, ky dang, ky tang
cua va » cua vat, chua va, cua van
nhat » nhan

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky sang mai hoi. hieu luc nhat cua va ((danh vi) or (dinh vi)) ((cua triet) or (va tuyen))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky sang mai hoi. hieu luc nhat cua va ((danh vi) OR (dinh vi)) ((cua triet) OR (va tuyen)).
• Adding a wildcard symbol may retrieve word variants: su sach ky sang mai hoi. hieu luc nhat cua va ((danh vi) or (dinh vi)) ((cua triet) or (va tuyen))*.