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