Perhaps you should try some spelling variations:
sach ngan » sach ngon, sach nha, sach han
cach ngan » cac ngan, cach nhanh, cac nganh
cong khi » cong thai, khong khi, co khi
cac anh » cac banh, cao anh, ca anh
su cac » tu cac, su cao, su can
anh so » anh son, anh co
so ki » so ky, so di, so li

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: (( su cac anh so ki đong luc ) OR ( su ((cach ngan) OR (sach ngan)) cong khi đong luc ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( su cac anh so ki đong luc ) or ( su ((cach ngan) OR (sach ngan)) cong khi đong luc ))~".
• Adding a wildcard symbol may retrieve word variants: (( su cac anh so ki đong luc ) or ( su ((cach ngan) OR (sach ngan)) cong khi đong luc ))*.