Perhaps you should try some spelling variations:
thien van » thi van
nam thuc » nam thuoc, am thuc, nam thu
van hanh » van thanh, ban hanh, van anh
cau tren » cu tren, dau tren, ca tren
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
va hanh » va thanh, va danh, ban hanh
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. ((lieu va) OR (thien van)) nam thuc ((va hanh) OR (van hanh)) vi cau tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang x hoi. ((lieu va) or (thien van)) nam thuc ((va hanh) OR (van hanh)) vi cau tren~".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang x hoi. ((lieu va) or (thien van)) nam thuc ((va hanh) OR (van hanh)) vi cau tren*.