Perhaps you should try some spelling variations:
sach nganh » sach ngan, sach tranh, cac nganh
nganh cong » nhanh chong, thanh cong
khong khi » khong he
cong thai » cong hai, hong thai, cong thanh
cong khi » co khi, cong ha, cong hai
so sach » so sanh, bo sach, co sach
su sach » vu sach

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