Perhaps you should try some spelling variations:
ve triet » va trien, su triet
van hanh » van thanh, ban hanh, van anh
nang mai » nang ma, nang tai, lang mai
hanh ki » hanh vi, hanh ky, hanh kien
luc van » luoc van, luu van, duc van
tu sach » thu sach, te sach, tu cach
mai hoi » mai khoi, dai hoi, lai hoi
vu nang » vuc nang, va nang, vu dang
su sach » so sach, vu sach
va cao » va cac, va co, va dao
va cam » va cham, va cac, va cai
ki ve » ke ve, gi ve, vi ve

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