Perhaps you should try some spelling variations:
sach ky » sac ky, sach y, sach ty
tu sach » thu sach, su sach, te sach
va thai » van thai, va tai, va tham
hieu va » lieu va, hieu qua
tuc va » thuc va, truc va, duc va
va cau » van cau, va cac, va dau
ve cau » ke cau, ve cac, le cau
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky nang x hoi. hieu va thai ((tuc va) OR (tuc xa)) danh ((va cau) or (ve cau)) tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x hoi. hieu va thai ((tuc va) OR (tuc xa)) danh ((va cau) OR (ve cau)) tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang x hoi. hieu va thai ((tuc va) OR (tuc xa)) danh ((va cau) or (ve cau)) tren".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x hoi. hieu va thai ((tuc va) OR (tuc xa)) danh ((va cau) or (ve cau)) tren*.