Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
ban hanh » ban hang
vuc nang » cuc nang, vu nang, chuc nang
nang mai » nang ma, nang tai, lang mai
mai khoi » mai khoa, tai khoa, cac khoi
hanh ki » hanh vi, hanh ky, hanh kien
xuc ban » duc ban, cuc ban, quoc ban
tu sach » thu sach, te sach, tu cach
su sach » so sach, vu sach
va cao » va cac, va co, va dao
va cam » va cham, va cac, va cai
ki su » ky su

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