Perhaps you should try some spelling variations:
"te sach y thuat co khi" » "te sach y thuat o khi", "toc sach y thuat co khi", "te sach my thuat co khi", "te sach kxy thuat co khi", "te sach ki thuat co khi"
"tu sach ky thuat do khi" » "tu sach ky thuat o khi", "tu sach kmy thuat do khi", "tu sach kkxy thuat do khi", "tu sach kki thuat do khi", "thu sach ky thuat do khi", "su sach ky thuat do khi", "tu cach ky thuat do khi", "tu sac ky thuat do khi", "tu sach ty thuat do khi", "tu sach kem thuat do khi", "tu sach ky thuat doi khi", "tu sach ky thuat do thi", "tu sach ky thuat dong khi"
"tu sach ky thuat bo khi" » "tu sach ky thuat bao khi", "tu sach ky thuat o khi", "tu sach ky thuat so khi", "tu sach kmy thuat bo khi", "tu sach kkxy thuat bo khi", "tu sach kki thuat bo khi", "thu sach ky thuat bo khi", "su sach ky thuat bo khi", "tu cach ky thuat bo khi", "tu sac ky thuat bo khi", "tu sach ty thuat bo khi", "tu sach kem thuat bo khi", "tu sach ky thuat bo chi", "tu sach ky thuat bo thi"

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 y thuat co khi") or ((("tu sach ky thuat do khi") OR ("tu sach ky thuat bo khi"))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("te sach y thuat co khi") OR ((("tu sach ky thuat do khi") OR ("tu sach ky thuat bo khi")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"te sach y thuat co khi\") or (((\"tu sach ky thuat do khi\") OR (\"tu sach ky thuat bo khi\"))))".
• Removing quotes may allow a broader search: (( te sach y thuat co khi ) or ((( tu sach ky thuat do khi ) OR ( tu sach ky thuat bo khi )))).
• Adding a wildcard symbol may retrieve word variants: (("te sach y thuat co khi") or ((("tu sach ky thuat do khi") OR ("tu sach ky thuat bo khi"))))*.