Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
cau tren » cu tren, dau tren, ca tren
hieu va » lieu va, hieu qua
dinh vi » dinh ve, dinh viet, dinh tri
danh di » danh du, xanh di, danh dien
hac tuc » thac toc, thai tuc
va hac » van hac, va khac, va cac
y nang » ky nang, ly nang, v nang
tuc va » thuc va, truc va, tuc xa
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: thu sach y nang ((x hoi) OR (xa hoi)). hieu va hac tuc va ((dinh vi) OR (danh di)) cau tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach y nang ((x hoi) OR (xa hoi)). hieu va hac tuc va ((dinh vi) or (danh di)) cau tren~".
• Adding a wildcard symbol may retrieve word variants: thu sach y nang ((x hoi) OR (xa hoi)). hieu va hac tuc va ((dinh vi) or (danh di)) cau tren*.