Perhaps you should try some spelling variations:
sach ngan » sach ngon, sach nha, sach han
cong thai » cong hai, hong thai, cong thanh
cong khi » khong khi, co khi, cong ha
sac anh » sac hanh, sat anh, sach danh
su sach » so sach, vu sach
su sac » su cac, su xac
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 sac anh so ki đong luc ) OR ( su sach ngan ((cong khi) OR (cong thai)) đong luc ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( su sac anh so ki đong luc ) or ( su sach ngan ((cong khi) OR (cong thai)) đong luc ))~".
• Adding a wildcard symbol may retrieve word variants: (( su sac anh so ki đong luc ) or ( su sach ngan ((cong khi) OR (cong thai)) đong luc ))*.