Perhaps you should try some spelling variations:
"su sach ngonh ky thuat co hoc" » "su sach ngon ky thuat co hoc", "su sach ngan ky thuat co hoc", "su sach nganh ky thuat co hoc", "su sach ngonh ky thuat do hoc", "su sach ngonh ky thuat o hoc", "vu sach ngonh ky thuat co hoc"
"so sach han hay thuyet hoa hoc" » "so sach han thay thuyet hoa hoc", "so sach han ly thuyet hoa hoc", "so sach han hoc thuyet hoa hoc", "so sach han hay thuyet va hoc", "so sach han hay huyet hoc hoc", "so sach tham hay thuyet hoa hoc", "so sach danh hay thuyet hoa hoc", "so sach nang hay thuyet hoa hoc", "so sanh han hay thuyet hoa hoc", "bo sach han hay thuyet hoa hoc", "co sach han hay thuyet hoa hoc", "so sach hang hay thuyet hoa hoc", "so sach han day thuyet hoa hoc", "so sach han tay thuyet hoa hoc"

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("su sach ngonh ky thuat co hoc") or ("so sach han hay thuyet hoa hoc"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("su sach ngonh ky thuat co hoc") OR ("so sach han hay thuyet hoa hoc"))*.
• Removing quotes may allow a broader search: (( su sach ngonh ky thuat co hoc ) or ( so sach han hay thuyet hoa hoc ))*.