Perhaps you should try some spelling variations:
"su sach kxy thuat do thi" » "su sach ki thuat do thi", "su sach my thuat do thi", "su sach ky thua do thi", "su sach kxy thuat o thi", "su sach xa thuat do thi", "su sach kem thuat do thi", "su sac ky thuat do thi", "so sach kxy thuat do thi", "vu sach kxy thuat do thi"
"vu bach va thiet bo khi" » "vu bach va thiet bi khi", "vu bach va thit bo khi", "vu bach va thien bao khi", "vu bach van thiet bo khi", "vu bach ha thiet bo khi", "vu sach va thiet bo khi", "vu bach va thiet co khi", "vu bach va thiet bo chi", "vu bach va thiet bo thi"
"tu cach ky thuat do thi" » "tu cach ky thuat o thi", "tu cac ky thuat do thi"

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("vu bach va thiet bo khi") or ((("tu cach ky thuat do thi") or ("su sach kxy thuat do thi"))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("vu bach va thiet bo khi") OR ((("tu cach ky thuat do thi") OR ("su sach kxy thuat do thi")))).
• Removing quotes may allow a broader search: (( vu bach va thiet bo khi ) or ((( tu cach ky thuat do thi ) or ( su sach kxy thuat do thi )))).
• Adding a wildcard symbol may retrieve word variants: (("vu bach va thiet bo khi") or ((("tu cach ky thuat do thi") or ("su sach kxy thuat do thi"))))*.