Perhaps you should try some spelling variations:
thien van » thi van
hieu van » hieu va, lieu va, hieu ve
nam thuc » nam thuoc, am thuc, nam thu
vinh cuu » dinh cuu, sinh cua, dinh cu
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
thuc va » thuc vat, thuc dan, thuc day
va hanh » van hanh, va thanh, va danh
vi cuu » vi luu
x hoi » xa hoi, o hoi, x ho

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