Perhaps you should try some spelling variations:
"tu sach ki thuat co khi" » "tu sach ki thuat o khi", "su sach ki thuat co khi", "te sach ki thuat co khi", "tu cach ki thuat co khi", "tu sach kinh thuat co khi", "tu sach bai thuat co khi", "tu sach kem thuat co khi"
"thu sach ky thuat co khi" » "thu sach ky thuat o khi", "thuat sach ky thuat co khi", "thuoc sach ky thuat co khi", "thu hoach ky thuat co khi", "thu sac ky thuat co khi", "thu sach y thuat co khi", "thu sach ty thuat co khi"
"thu sach my thuat do khi" » "thuat sach my thuat do khi", "thuoc sach my thuat do khi", "thu hoach my thuat do khi", "thu sach va thuat do khi", "thu sach my thuat o khi", "thu sach y thuat do khi", "thu sach ty thuat do khi", "thu sach mau thuat do khi", "thu sach my thuat doi khi", "thu sach my thuat do thi", "thu sach my thuat bo khi"

Try widening your search to All Fields.

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 ((("thu sach my thuat do khi") or ("thu sach ky thuat co khi"))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("tu sach ki thuat co khi") OR ((("thu sach my thuat do khi") OR ("thu sach ky thuat co khi")))).
• Removing quotes may allow a broader search: (( tu sach ki thuat co khi ) or ((( thu sach my thuat do khi ) or ( thu sach ky thuat co khi )))).
• Adding a wildcard symbol may retrieve word variants: (("tu sach ki thuat co khi") or ((("thu sach my thuat do khi") or ("thu sach ky thuat co khi"))))*.