Perhaps you should try some spelling variations:
"so sach kinh thuat bo khi" » "so sach ki thuat bo khi", "so sach dich thuat bo khi", "so sach ninh thuan bo khi", "so sach kinh thuat bao khi", "so sach kinh thuat o khi", "so sach kinh thuat so khi", "so sanh kinh thuat bo khi", "bo sach kinh thuat bo khi", "co sach kinh thuat bo khi", "so sach kinh thuat bo chi", "so sach kinh thuat bo thi"
"vu sach dao thuat co khi" » "vu sach dao phat co khi", "vu sach va thuat co khi", "vu sach cac thuat co khi", "vu lanh dao thuat co khi", "vu sach dao thuat o khi", "vu bach dao thuat co khi", "vu khach dao thuat co khi"
"su sach ky thuat do khi" » "su sach ky thuat o khi", "su sac ky thuat do khi", "su sach y thuat do khi", "su sach ty thuat do khi", "su sach ky thuat doi khi", "su sach ky thuat do thi", "su sach ky thuat dong 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: (("vu sach dao thuat co khi") or ((("so sach kinh thuat bo khi") or ("su sach ky thuat do khi"))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("vu sach dao thuat co khi") OR ((("so sach kinh thuat bo khi") OR ("su sach ky thuat do khi")))).
• Removing quotes may allow a broader search: (( vu sach dao thuat co khi ) or ((( so sach kinh thuat bo khi ) or ( su sach ky thuat do khi )))).
• Adding a wildcard symbol may retrieve word variants: (("vu sach dao thuat co khi") or ((("so sach kinh thuat bo khi") or ("su sach ky thuat do khi"))))*.