Perhaps you should try some spelling variations:
sach nganh » sach ngan, sach tranh, cac nganh
cac thanh » bac thanh, cach nhanh, ban thanh
chong khi » khong khi, cong khi, chong lai
chong hiv » among hiv, chong li, chong vi
su sach » so sach, vu sach
su cac » tu cac, su cao, su can
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 nganh y khi đong luc ) OR ( su cac thanh ((chong khi) OR (chong hiv)) đong luc ))~.
• Adding a wildcard symbol may retrieve word variants: (( su sach nganh y khi đong luc ) or ( su cac thanh ((chong khi) or (chong hiv)) đong luc ))*.