Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
van hanh » van thanh, ban hanh, van anh
tuc van » thuc van, truc van, tuc va
dao tuc » dao duc
hieu va » lieu va, hieu qua
tu sach » thu sach, su sach, te sach
vu nang » vuc nang, va nang, vu dang
va dao » ca dao
v nang » va nang, van nang, voi nang
vi cau » va cau, ve cau, di cau
x hoi » o hoi, x ho, 5 hoi

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: tu sach ((v nang) OR (vu nang)) ((x hoi) OR (xa hoi)). hieu va dao tuc van hanh vi cau tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((v nang) OR (vu nang)) ((x hoi) or (xa hoi)). hieu va dao tuc van hanh vi cau tren~".
• Adding a wildcard symbol may retrieve word variants: tu sach ((v nang) OR (vu nang)) ((x hoi) or (xa hoi)). hieu va dao tuc van hanh vi cau tren*.