Perhaps you should try some spelling variations:
van thanh » ban thanh, van tuan
thanh vi » hanh vi, thanh va, thanh ve
su sach » so sach, vu sach
duc van » duc va, duc tan, duc manh
su viet » so viet
ky tang » ky nang, ky dang, kho tang
ky lang » ky nang, ky dang, tay lang
ve cai » va cai, ve tai, ve cau
ve cac » va cac, vien cac
vi su » va su, ve su, ki su

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 tang)) xa hoi. hieu ((ve cai) or (ve cac)) duc van thanh vi su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((ky lang) OR (ky tang)) xa hoi. hieu ((ve cai) OR (ve cac)) duc van thanh vi su viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((ky lang) OR (ky tang)) xa hoi. hieu ((ve cai) or (ve cac)) duc van thanh vi su viet".
• Adding a wildcard symbol may retrieve word variants: su sach ((ky lang) OR (ky tang)) xa hoi. hieu ((ve cai) or (ve cac)) duc van thanh vi su viet*.