Perhaps you should try some spelling variations:
"thu sach ki thuat co khi" » "thuat sach ki thuat co khi", "thuoc sach ki thuat co khi", "thu hoach ki thuat co khi", "thu sach ky thuat co khi", "thu sach ki thuat o khi", "thu sach kinh thuat co khi", "thu sach bai thuat co khi", "thu sach kem thuat co khi"
"tu sach y thuat ho chi" » "tu sach y thuat hoa chi", "tu sach y thuat o chi", "tu sach y thuat so chi", "su sach y thuat ho chi", "te sach y thuat ho chi", "tu cach y thuat ho chi", "tu sach ky thuat ho chi", "tu sach my thuat ho chi", "tu sach kxy thuat ho chi"
"tu sach y thuat do thi" » "tu sach y thuat o thi", "su sach y thuat do thi", "te sach y thuat do thi", "tu cach y thuat do thi", "tu sach ky thuat do thi", "tu sach my thuat do thi", "tu sach kxy thuat do 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: (((("thu sach ki thuat co khi") or ("tu sach y thuat ho chi"))) or ("tu sach y thuat do thi"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("thu sach ki thuat co khi") OR ("tu sach y thuat ho chi"))) OR ("tu sach y thuat do thi")).
• Removing quotes may allow a broader search: (((( thu sach ki thuat co khi ) or ( tu sach y thuat ho chi ))) or ( tu sach y thuat do thi )).
• Adding a wildcard symbol may retrieve word variants: (((("thu sach ki thuat co khi") or ("tu sach y thuat ho chi"))) or ("tu sach y thuat do thi"))*.