Perhaps you should try some spelling variations:
sach nganh » sach ngan, sach danh, cach nhanh
sach tranh » canh tranh
cac nganh » hoc nganh
cong khi » cong thai, khong khi, co khi
su sach » so sach, vu 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.

• If you are trying to use Boolean operators, they must be ALL CAPS: (( su sach tranh y khi đong luc ) OR ( su ((sach nganh) OR (cac nganh)) cong khi đong luc ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( su sach tranh y khi đong luc ) or ( su ((sach nganh) OR (cac nganh)) cong khi đong luc ))~".
• Adding a wildcard symbol may retrieve word variants: (( su sach tranh y khi đong luc ) or ( su ((sach nganh) OR (cac nganh)) cong khi đong luc ))*.