Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve 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
sach vu » sach tu, sach uu, sach xu
mai hoi » mai khoi, dai hoi, lai hoi
sach va » sach xa, sach ha, sach dao
va cao » va cac, va co, va dao
va cai » va cac, va bai, va dai
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 vu) OR (sach va)) nang mai hoi. hieu ((va cai) or (va cao)) luc van hanh ki su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach vu) OR (sach va)) nang mai hoi. hieu ((va cai) OR (va cao)) luc van hanh ki su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach vu) OR (sach va)) nang mai hoi. hieu ((va cai) or (va cao)) luc van hanh ki su triet".
• Adding a wildcard symbol may retrieve word variants: tu ((sach vu) OR (sach va)) nang mai hoi. hieu ((va cai) or (va cao)) luc van hanh ki su triet*.