Perhaps you should try some spelling variations:
kki thuat » ki thuat, khoi thuat, ky thuat
thuat bo » thuat bao, thuat o, thuat co
thuat do » thuat o
tu cach » tu cac
te sach » toc sach
sach ky » sach y, sach ty, sach kem
sac ky » cac ky, sai ky
bo thi » bo thit, do thi, bo tai
do khi » doi khi, do thi, co 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 cach) or (te sach)) kki thuat do khi ) or ( su ((sach ky) OR (sac ky)) thuat bo thi ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( ((tu cach) OR (te sach)) kki thuat do khi ) OR ( su ((sach ky) OR (sac ky)) thuat bo thi )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( ((tu cach) or (te sach)) kki thuat do khi ) or ( su ((sach ky) OR (sac ky)) thuat bo thi ))".
• Adding a wildcard symbol may retrieve word variants: (( ((tu cach) or (te sach)) kki thuat do khi ) or ( su ((sach ky) OR (sac ky)) thuat bo thi ))*.