Perhaps you should try some spelling variations:
sach nganh » sach ngan, cac nganh, sach danh
nganh cong » nhanh chong, thanh cong
sach tranh » canh tranh
cong khi » cong thai, khong khi, co khi
so sach » so sanh, bo sach, co sach
tranh y » trinh y, tranh o, tranh 30
y khi » ly khi, ky khi, my khi

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( so sach nganh cong khi đong luc ) or ( so sach tranh y khi đong luc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( so sach nganh cong khi đong luc ) OR ( so sach tranh y khi đong luc )).
• Adding a wildcard symbol may retrieve word variants: (( so sach nganh cong khi đong luc ) or ( so sach tranh y khi đong luc ))*.