Perhaps you should try some spelling variations:
nang dai » nang dau, nang tai, lang dai
nam truc » nam truoc, nam thuc, nam trung
van hanh » van thanh, ban hanh, van anh
vinh cuu » dinh cuu, sinh cua, dinh cu
dai hoi » dai hoc, dai hai, dai moi
hieu va » lieu va, hieu qua
va hanh » va thanh, va danh, ban hanh
tu sac » tu sach, tu cac, tu san
sac ky » cac ky, sai ky
va nam » van nam, ha nam, va nay
vi cuu » vi luu

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sac ky nang dai hoi. hieu va nam truc ((va hanh) OR (van hanh)) ((vi cuu) or (vinh cuu)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ky nang dai hoi. hieu va nam truc ((va hanh) OR (van hanh)) ((vi cuu) OR (vinh cuu)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sac ky nang dai hoi. hieu va nam truc ((va hanh) OR (van hanh)) ((vi cuu) or (vinh cuu)) tre".
• Adding a wildcard symbol may retrieve word variants: tu sac ky nang dai hoi. hieu va nam truc ((va hanh) OR (van hanh)) ((vi cuu) or (vinh cuu)) tre*.