Perhaps you should try some spelling variations:
"tu sach kxmky thuat o khi" » "tu sach kxy thuat o khi", "thu sach kxmky thuat o khi", "su sach kxmky thuat o khi", "tu cach kxmky thuat o khi", "tu sach kxmky thuat do khi", "tu sach kxmky thuat bo khi"
"su bac ky thuat bao khi" » "su bac ky thuat bai khi", "su bac ky thuat giao khi", "su bac ky thuat do khi", "su bac ky thuat bao chi", "su bac ky thuat ban khi", "su bac ky thuat bao kha", "xu bac ky thuat bao khi", "du bac ky thuat bao khi", "su cac ky thuat bao khi", "su ban ky thuat bao khi", "su sac ky thuat bao khi", "su bac ky thuat babo khi"
"te sach ky thuat co khi" » "te sach ky thuat do khi", "toc sach ky thuat co khi", "te sac ky thuat co khi", "te sach y thuat co khi", "te sach ty thuat co khi", "te sach ky thuat cbo 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: (("te sach ky thuat co khi") or ((("su bac ky thuat bao khi") or ("tu sach kxmky thuat o khi"))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("te sach ky thuat co khi") OR ((("su bac ky thuat bao khi") OR ("tu sach kxmky thuat o khi")))).
• Removing quotes may allow a broader search: (( te sach ky thuat co khi ) or ((( su bac ky thuat bao khi ) or ( tu sach kxmky thuat o khi )))).
• Adding a wildcard symbol may retrieve word variants: (("te sach ky thuat co khi") or ((("su bac ky thuat bao khi") or ("tu sach kxmky thuat o khi"))))*.