Perhaps you should try some spelling variations:
"so sanh ki thuat hoc noi" » "so sanh ki thuat hoa noi", "so sanh ki thuat doc noi", "so sanh ki thuat thuc noi", "so sanh ky thuat hoc noi", "do sanh ki thuat hoc noi", "so sanh ki thuat hoc nuoc"
"so sach y thuat hoc khia" » "so sach y thuat hoa khia", "so sach y thuat doc khia", "so sach y thuat thuc khia", "so sach y thuat hoc khoa", "so sach y thuat hoc chia", "so sach y thuat hoc khi", "bo sach y thuat hoc khia", "co sach y thuat hoc khia", "hoc sach y thuat hoc khia", "so sach ky thuat hoc khia", "so sach my thuat hoc khia", "so sach kxy thuat hoc khia"
"te sach y thuat do thi" » "te sach y thuat o thi", "te sach ky thuat do thi", "te sach my thuat do thi", "te sach kxy thuat do thi", "toc sach y thuat do thi"

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: (((("so sanh ki thuat hoc noi") OR ("so sach y thuat hoc khia"))) OR ("te sach y thuat do thi"))~.
• Removing quotes may allow a broader search: (((( so sanh ki thuat hoc noi ) or ( so sach y thuat hoc khia ))) or ( te sach y thuat do thi ))~.
• Adding a wildcard symbol may retrieve word variants: (((("so sanh ki thuat hoc noi") or ("so sach y thuat hoc khia"))) or ("te sach y thuat do thi"))*.