Perhaps you should try some spelling variations:
thuat duoc » thuat quoc, thuat doc, thuat do
kkxy thuat » kxy thuat
toc sach » hoc sach, doc sach, thuoc sach
duoc hoi » quoc hoi, duoc hoc, duoc si
sach ky » sac ky, sach ty, sach kem
thuat o » thuat do
tu sach » thu sach, su sach, te sach
y thuat » my thuat, kxy thuat, ki thuat
o khi » co 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: (((( toc sach ky thuat o khi ) or ( toc sach kkxy thuat o khi ))) or ( tu sach y thuat duoc hoi ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((( toc sach ky thuat o khi ) OR ( toc sach kkxy thuat o khi ))) OR ( tu sach y thuat duoc hoi )).
• Adding a wildcard symbol may retrieve word variants: (((( toc sach ky thuat o khi ) or ( toc sach kkxy thuat o khi ))) or ( tu sach y thuat duoc hoi ))*.