Perhaps you should try some spelling variations:
"te sach nganh ki thuat so hoc" » "te sach ngan ki thuat so hoc", "te sach tranh ki thuat so hoc", "te cac nganh ki thuat so hoc", "te sach nganh ky thuat so hoc", "te sach nganh ke thuat so hoc", "te sach nganh vi thuat so hoc", "te sach nganh ki thuat do hoc", "te sach nganh ki thuat o hoc", "te sach nganh ki thuat co hoc", "toc sach nganh ki thuat so hoc", "te sach nganh ki thuat mo hoc", "te sach nganh ki thuat so hoa"
"tu sach van ky thuat mon hoc" » "tu sach van ky thuat don hoc", "tu sach van ky thuat mo hoc", "tu sach van ky thuat moi hoc", "tu sach han ky thuat mon hoc", "tu sach va ky thuat mon hoc", "tu bach van ky thuat mon hoc", "thu sach van ky thuat mon hoc", "su sach van ky thuat mon hoc", "tu cach van ky thuat mon hoc", "tu sach van ky thuat toan hoc", "tu sach van ky thuat dong hoc"

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 nganh ki thuat so hoc") OR ("tu sach van ky thuat mon hoc"))~.
• Removing quotes may allow a broader search: (( te sach nganh ki thuat so hoc ) or ( tu sach van ky thuat mon hoc ))~.
• Adding a wildcard symbol may retrieve word variants: (("te sach nganh ki thuat so hoc") or ("tu sach van ky thuat mon hoc"))*.