Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
nang mai » nang ma, nang tai, lang mai
ban hanh » ban hang
van hanh » van thanh, van anh, van ban
tu sach » thu sach, su sach, te sach
sach vu » sach va, sach tu, sach uu
mai hoi » mai khoi, dai hoi, lai hoi
vu nang » vuc nang, va nang, vu dang
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 vu nang mai hoi. hieu ((va cam) or (va cao)) luc ((van hanh) or (ban hanh)) ki su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach vu nang mai hoi. hieu ((va cam) OR (va cao)) luc ((van hanh) OR (ban hanh)) ki su triet.
• Adding a wildcard symbol may retrieve word variants: tu sach vu nang mai hoi. hieu ((va cam) or (va cao)) luc ((van hanh) or (ban hanh)) ki su triet*.