Perhaps you should try some spelling variations:
"thu sach kxy thuat doc khi" » "thu sach kxy thuat duoc khi", "thu sach kxy thuat do khi", "thu sach kxy thuat doi khi", "thu sach ky thuat doc khi", "thu sach my thuat doc khi", "thu sach ky thua doc khi", "thuat sach kxy thuat doc khi", "thuoc sach kxy thuat doc khi", "thu hoach kxy thuat doc khi", "thu sach xa thuat doc khi", "thu sach kem thuat doc khi", "thu sac ky thuat doc khi", "thu sach kxy thuat hoc khi", "thu sach kxy thuat hoc khoi"
"tu sach ki thuat o khi" » "tu sach ky thuat o khi", "su sach ki thuat o khi", "te sach ki thuat o khi", "tu cach ki thuat o khi", "tu sach kinh thuat o khi", "tu sach bai thuat o khi", "tu sach kem thuat o khi", "tu sach ki thuat do khi", "tu sach ki thuat co khi", "tu sach ki thuat bo 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 sach ki thuat o khi") or ("thu sach kxy thuat doc khi"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("tu sach ki thuat o khi") OR ("thu sach kxy thuat doc khi")).
• Removing quotes may allow a broader search: (( tu sach ki thuat o khi ) or ( thu sach kxy thuat doc khi )).
• Adding a wildcard symbol may retrieve word variants: (("tu sach ki thuat o khi") or ("thu sach kxy thuat doc khi"))*.