Perhaps you should try some spelling variations:
nang doc » nang luc
van hanh » van thanh, ban hanh, van anh
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
cac xuc » cam xuc, cac nuoc, chat xuc
xuc van » duc van, luc van, vuc van
tai cuu » tai cuc, tai cua, thai cua
nang o » nang co, nang ho, nang ro
ve cac » va cac, vien cac

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((nang o) OR (nang doc)) hoi. hieu ve cac xuc van hanh ((tai cuu) OR (tai buu)) tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky ((nang o) or (nang doc)) hoi. hieu ve cac xuc van hanh ((tai cuu) OR (tai buu)) tre~".
• Adding a wildcard symbol may retrieve word variants: su sach ky ((nang o) or (nang doc)) hoi. hieu ve cac xuc van hanh ((tai cuu) OR (tai buu)) tre*.