Perhaps you should try some spelling variations:
"te sach kxy thuat do thi" » "te sach ki thuat do thi", "te sach my thuat do thi", "te sach ky thua do thi", "te sach xa thuat do thi", "te sach kem thuat do thi", "te sac ky thuat do thi", "toc sach kxy thuat do thi", "te sach kxmy thuat do thi", "te sach kxki thuat do thi", "te sach kxva thuat do thi"
"thu hoach ky thuat o khi" » "thu hoach xay thuat o khi", "thu hanh ky thuat o khi", "thu hoa ky thuat o khi", "thu hoach kmy thuat o khi", "thu hoach kki thuat o khi", "thu hoach kva thuat o khi", "thu hoach ky thuat co khi", "thu hoach ky thuat bo khi"
"te sach y thuat do thi" » "toc sach y thuat do thi", "te sach my thuat do thi", "te sach ki thuat do thi", "te sach va thuat do thi"

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

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