Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
mai khoi » mai khoa, tai khoa, cac khoi
hieu va » lieu va, hieu qua
hanh ki » hanh vi, hanh ky, hanh kien
luc van » luoc van, luu van, duc van
cam luc » cam xuc, cau luc
tu sach » thu sach, su sach, te sach
sach vu » sach va, sach tu, sach uu
mai hoi » dai hoi, lai hoi, mai doi
vu nang » vuc nang, va nang, vu dang
su viet » so viet
va cam » va cham, va cac, va cao
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) OR (mai khoi)). hieu va cam luc van hanh ki su viet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach vu nang ((mai hoi) OR (mai khoi)). hieu va cam luc van hanh ki su viet".
• Adding a wildcard symbol may retrieve word variants: tu sach vu nang ((mai hoi) OR (mai khoi)). hieu va cam luc van hanh ki su viet*.