Perhaps you should try some spelling variations:
kxy thuat » ky thuat, ki thuat, my thuat
sach kxy » sach xa, sach kem, sac ky
thu sach » tu sach, thuat sach, thuoc sach
su sach » so sach, vu sach
y thuat » ky thuat, my thuat, ki thuat
do khi » doi khi, do thi, co khi
o khi » co 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 sach kxy thuat do khi ) OR ( thu sach y thuat o khi ))~.
• Adding a wildcard symbol may retrieve word variants: (( su sach kxy thuat do khi ) or ( thu sach y thuat o khi ))*.