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 duc, cua tu, cua thuoc
y nang » ky nang, ly nang, v nang
ve cau » ke cau, va cau, ve cac
te cua » tue cua, le cua, de cua
x hoi » xa hoi, o hoi, 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: toc sach y nang ((x hoi) OR (x ho)). hieu ((ve cau) OR (ket cau)) duc van hanh te cua tuc~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach y nang ((x hoi) OR (x ho)). hieu ((ve cau) or (ket cau)) duc van hanh te cua tuc~".
• Adding a wildcard symbol may retrieve word variants: toc sach y nang ((x hoi) OR (x ho)). hieu ((ve cau) or (ket cau)) duc van hanh te cua tuc*.