Perhaps you should try some spelling variations:
tinh lap » trinh lap, tinh lao, dinh lap
so sach » so sanh, bo sach, co sach
hieu va » lieu va, hieu qua
lap cua » lai cua, tap cua, lam cua
va tinh » may tinh
cac duc » cac du, cao duc, cac dac
hieu ve » hieu van
sach ky » sac ky, sach y, sach ty
mai hoi » mai khoi, dai hoi, lai hoi
ky dang » ky nang, ky danh
cua te » cua tu

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

• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ky dang ((mai hoi) OR (xa hoi)). ((hieu ve) OR (hieu va)) cac duc va tinh lap cua te~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ky dang ((mai hoi) or (xa hoi)). ((hieu ve) OR (hieu va)) cac duc va tinh lap cua te~".
• Adding a wildcard symbol may retrieve word variants: so sach ky dang ((mai hoi) or (xa hoi)). ((hieu ve) OR (hieu va)) cac duc va tinh lap cua te*.