Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
duc van » duc va, duc tan, duc manh
hanh te » hanh tu, hanh ve, hanh de
cua tuc » cua tu, cua thuoc, luat tuc
cua duc » cua nuoc, cua quoc
y nang » ky nang, ly nang, v nang
ve cau » ke cau, va cau, ve cac
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: toc sach y nang x hoi. hieu ((ve cau) OR (ket cau)) duc van hanh te ((cua tuc) OR (cua duc))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach y nang x hoi. hieu ((ve cau) or (ket cau)) duc van hanh te ((cua tuc) OR (cua duc))~".
• Adding a wildcard symbol may retrieve word variants: toc sach y nang x hoi. hieu ((ve cau) or (ket cau)) duc van hanh te ((cua tuc) OR (cua duc))*.