Perhaps you should try some spelling variations:
su sach » vu sach
tinh vi » trinh vi, tinh voi, tinh va
hieu ve » hieu va, hieu van
ty nang » ky nang, ty xang, ty hang
so sach » so sanh, bo sach, co sach
ve cac » va cac, vien cac
x hoi » xa hoi, o hoi, x ho
vi va » vi van, vai va, vu va
thiet » thieu

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) OR (so sach)) ty nang x hoi. hieu ve cac ((dai va) or (mai va)) tinh vi va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (so sach)) ty nang x hoi. hieu ve cac ((dai va) OR (mai va)) tinh vi va thiet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) OR (so sach)) ty nang x hoi. hieu ve cac ((dai va) or (mai va)) tinh vi va thiet".
• Adding a wildcard symbol may retrieve word variants: ((su sach) OR (so sach)) ty nang x hoi. hieu ve cac ((dai va) or (mai va)) tinh vi va thiet*.