Perhaps you should try some spelling variations:
"bo sach my thuat hoc khoa" » "bo sach my thuat hoa khoa", "bo sach my thuat doc khoa", "bo sach my thuat thuc khoa", "bo sach ky thuat hoc khoa", "bo sach ki thuat hoc khoa", "bo sach va thuat hoc khoa", "bo sach my thuat hoc pho", "co sach my thuat hoc khoa", "hoc sach my thuat hoc khoa", "bo sach ty thuat hoc khoa", "bo sach mau thuat hoc khoa", "bo sach moi thuat hoc khoa", "bo sach mky thuat hoc khoa", "bo sach mkxy thuat hoc khoa", "bo sach mki thuat hoc khoa"
"so sach y thuat hoc ki" » "so sach y thuat hoa ki", "so sach y thuat doc ki", "so sach y thuat thuc ki", "so sanh y thuat hoc ki", "co sach y thuat hoc ki", "hoc sach y thuat hoc ki", "so sach ky thuat hoc ki", "so sach kxy thuat hoc ki", "so sach ki thuat hoc ki", "so sach y thuat hoc ky", "so sach y thuat hoc kinh", "so sach y thuat hoc khoi"
"te sach y thuat do thi" » "te sach y thuat o thi", "te sach ky thuat do thi", "te sach kxy thuat do thi", "te sach ki 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: (((("bo sach my thuat hoc khoa") OR ("so sach y thuat hoc ki"))) OR ("te sach y thuat do thi"))~.
• Removing quotes may allow a broader search: (((( bo sach my thuat hoc khoa ) or ( so sach y thuat hoc ki ))) or ( te sach y thuat do thi ))~.
• Adding a wildcard symbol may retrieve word variants: (((("bo sach my thuat hoc khoa") or ("so sach y thuat hoc ki"))) or ("te sach y thuat do thi"))*.