Perhaps you should try some spelling variations:
va trien » va truyen, va thiet, va tuyen
va triet » va thiet, ve triet, cua triet
van hanh » van thanh, ban hanh, van anh
hanh su » hanh sua, hinh su, hanh tu
luc van » luoc van, luu van, duc van
cac luc » cau luc, coc luc, cac nuoc
tu sach » thu sach, te sach, tu cach
sang ma » tang ma, nang ma, sang tao
ky sang » ky nang, ky dang, ky tang
su sach » so sach, vu sach
hieu va » lieu va, hieu qua
ma hoi » mai hoi, xa hoi, ma hoa

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) or (su sach)) ky sang ma hoi. hieu va cac luc van hanh su ((va triet) OR (va trien))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) ky sang ma hoi. hieu va cac luc van hanh su ((va triet) OR (va trien)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (su sach)) ky sang ma hoi. hieu va cac luc van hanh su ((va triet) OR (va trien))".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) ky sang ma hoi. hieu va cac luc van hanh su ((va triet) OR (va trien))*.