Perhaps you should try some spelling variations:
ki thuat » ky thuat
thuat co » thuat do, thuat o
sach kxy » sach kem, sac ky, sach y
tu sach » thu sach, su sach, te sach
sach ki » sach kinh, sach bai, sach kem
sach xa » sach dao, sach nha, sach bai
bo khi » bo chi
bo thi » bo thit, do thi, bo tai

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 co khi ) or ( su ((sach kxy) OR (sach xa)) thuat ((bo khi) or (bo thi)) ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach ki thuat co khi ) OR ( su ((sach kxy) OR (sach xa)) thuat ((bo khi) OR (bo thi)) )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tu sach ki thuat co khi ) or ( su ((sach kxy) OR (sach xa)) thuat ((bo khi) or (bo thi)) ))".
• Adding a wildcard symbol may retrieve word variants: (( tu sach ki thuat co khi ) or ( su ((sach kxy) OR (sach xa)) thuat ((bo khi) or (bo thi)) ))*.