Perhaps you should try some spelling variations:
hieu viec » nhieu viec, hieu ve, sieu viet
va triet » va thiet, va trien, ve triet
van hanh » van thanh, ban hanh, van anh
ky dang » ky nang, ky danh
cac tac » cac toc, cac bac, cac dac
cac dai » cac dan, cac bai, can dai
ky lang » ky nang, ky tang, tay lang
su sach » so sach, vu sach
vi va » vi van, vai va, vu va

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ((ky lang) OR (ky dang)) xa hoi. hieu viec ((cac tac) or (cac dai)) van hanh vi va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((ky lang) OR (ky dang)) xa hoi. hieu viec ((cac tac) OR (cac dai)) van hanh vi va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((ky lang) OR (ky dang)) xa hoi. hieu viec ((cac tac) or (cac dai)) van hanh vi va triet".
• Adding a wildcard symbol may retrieve word variants: su sach ((ky lang) OR (ky dang)) xa hoi. hieu viec ((cac tac) or (cac dai)) van hanh vi va triet*.