Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
cao duc » dao duc, cao suc, giao duc
ty nang » ky nang, ty hang, ly nang
hieu ve » hieu va, hieu van
cac duc » cac du, cac dac, cac nuoc
vi cua » vai cua, di cua
cua cu » cua chu, cua cau, cua su

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ((ty nang) OR (ty xang)) xa hoi. hieu ve ((cac duc) or (cao duc)) van hanh vi cua cu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((ty nang) OR (ty xang)) xa hoi. hieu ve ((cac duc) OR (cao duc)) van hanh vi cua cu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((ty nang) OR (ty xang)) xa hoi. hieu ve ((cac duc) or (cao duc)) van hanh vi cua cu".
• Adding a wildcard symbol may retrieve word variants: toc sach ((ty nang) OR (ty xang)) xa hoi. hieu ve ((cac duc) or (cao duc)) van hanh vi cua cu*.