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