Perhaps you should try some spelling variations:
thien van » thi van
hieu van » hieu va, lieu va, hieu ve
nam thuc » nam thuoc, nam thu, nam tu
cau tren » cu tren, dau tren, ca tren
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
va hanh » van hanh, va thanh, va danh
vi cau » va cau, ve cau, di cau
x hoi » xa hoi, o hoi, x ho

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 x hoi. ((hieu van) OR (thien van)) ((nam thuc) OR (am thuc)) va hanh vi cau tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang x hoi. ((hieu van) or (thien van)) ((nam thuc) OR (am thuc)) va hanh vi cau tren~".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang x hoi. ((hieu van) or (thien van)) ((nam thuc) OR (am thuc)) va hanh vi cau tren*.