Perhaps you should try some spelling variations:
so sach » so sanh, bo sach, co sach
hieu ve » hieu va, hieu van
nang ma » tang ma, sang ma, nang cao
ve cam » ve cham, ve cac, va cam
y nang » ky nang, ly nang, v nang
ma hoi » mai hoi, xa hoi, ma hoa
va dao » ca dao
xac va » tac va, ac va, bac va

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach y nang ma hoi. hieu ve cam ((xac va) or (duc va)) hanh ((va dau) OR (va dao)) tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach y nang ma hoi. hieu ve cam ((xac va) OR (duc va)) hanh ((va dau) OR (va dao)) tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach y nang ma hoi. hieu ve cam ((xac va) or (duc va)) hanh ((va dau) OR (va dao)) tren".
• Adding a wildcard symbol may retrieve word variants: so sach y nang ma hoi. hieu ve cam ((xac va) or (duc va)) hanh ((va dau) OR (va dao)) tren*.