Perhaps you should try some spelling variations:
"tu san ki thuat do thi" » "tu san ki thuat o thi", "thu san ki thuat do thi", "tu ban ki thuat do thi", "tu can ki thuat do thi", "tu son ki thuat do thi", "tu san kinh thuat do thi"
"tu sai ky thuat co khi" » "tu sai ky thuat o khi", "tu cai ky thuat co khi", "tu lai ky thuat co khi", "tu mai ky thuat co khi", "tu sac ky thuat co khi"
"tu bai ky thuat co khi" » "tu bai ky thuat o khi", "tu ban ky thuat co khi", "tu bat ky thuat co khi", "te bai ky thuat co khi", "tu bac ky thuat co khi", "tu dai ky thuat co khi"

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

• If you are trying to use Boolean operators, they must be ALL CAPS: (("tu san ki thuat do thi") OR ((("tu sai ky thuat co khi") OR ("tu bai ky thuat co khi"))))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"tu san ki thuat do thi\") or (((\"tu sai ky thuat co khi\") OR (\"tu bai ky thuat co khi\"))))~".
• Removing quotes may allow a broader search: (( tu san ki thuat do thi ) or ((( tu sai ky thuat co khi ) OR ( tu bai ky thuat co khi ))))~.
• Adding a wildcard symbol may retrieve word variants: (("tu san ki thuat do thi") or ((("tu sai ky thuat co khi") OR ("tu bai ky thuat co khi"))))*.