Perhaps you should try some spelling variations:
kxki thuat » khoi thuat, kxy thuat
ki thuat » ky thuat
thuat co » thuat do
tu sach » thu sach, te sach, tu cach
sach ki » sach kinh, sach bai, sach kem
thuat o » thuat do
su sach » so sach, vu sach
o khi » bo khi

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (( tu sach ki thuat o khi ) or ( su sach kxki thuat co khi ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach ki thuat o khi ) OR ( su sach kxki thuat co khi )).
• Adding a wildcard symbol may retrieve word variants: (( tu sach ki thuat o khi ) or ( su sach kxki thuat co khi ))*.