Perhaps you should try some spelling variations:
thuat co » thuat do
so sach » so sanh, bo sach, co sach
y thuat » my thuat, kxy thuat, ki thuat
vu sach » vu bach, su sach, vu khach
sach ky » sach ty, sach kem, sach hay
thuat o » thuat do
su sac » su sach, su cac, su xac
sac ky » cac ky, sai ky
o khi » bo 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 sac ky thuat co khi ) OR ( so sach y thuat co khi ))) OR ( vu sach ky thuat o khi ))~.
• Adding a wildcard symbol may retrieve word variants: (((( su sac ky thuat co khi ) or ( so sach y thuat co khi ))) or ( vu sach ky thuat o khi ))*.