Perhaps you should try some spelling variations:
kem thuat » kiem thuat, ki thuat, ve thuat
sach kem » hanh kem
vu sach » vu bach, su sach, vu khach
so sach » so sanh, bo sach, co sach
y thuat » my thuat, kxy thuat, ki thuat
sach ky » sac ky, sach ty, sach hay
do khi » doi khi, do thi, bo khi
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: (((( vu sach kem thuat o khi ) or ( so sach y thuat co khi ))) or ( so sach ky thuat do khi ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((( vu sach kem thuat o khi ) OR ( so sach y thuat co khi ))) OR ( so sach ky thuat do khi )).
• Adding a wildcard symbol may retrieve word variants: (((( vu sach kem thuat o khi ) or ( so sach y thuat co khi ))) or ( so sach ky thuat do khi ))*.