Perhaps you should try some spelling variations:
"su sach ki thuat do khi" » "so sach ki thuat do khi", "vu sach ki thuat do khi", "su sach kinh thuat do khi", "su sach bai thuat do khi", "su sach kem thuat do khi", "su sach ki thuat doi khi", "su sach ki thuat do thi", "su sach ki thuat bo khi"
"su tai ky thuat co khi" » "su thi ky thuat co khi", "tu tai ky thuat co khi", "su thai ky thuat co khi", "su trai ky thuat co khi", "su sai ky thuat co khi"
"su cac ky thuat o thi" » "tu cac ky thuat o thi", "su cao ky thuat o thi", "su can ky thuat o thi", "su cac ky thuat do thi", "su cac ky thuat vo thi", "su cac ky thuat lo thi"

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("su sach ki thuat do khi") or ((("su tai ky thuat co khi") or ("su cac ky thuat o thi"))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("su sach ki thuat do khi") OR ((("su tai ky thuat co khi") OR ("su cac ky thuat o thi"))))*.
• Removing quotes may allow a broader search: (( su sach ki thuat do khi ) or ((( su tai ky thuat co khi ) or ( su cac ky thuat o thi ))))*.