Perhaps you should try some spelling variations:
"vay khach ngan ly thuyet hoa hoc" » "vay khach san ly thuyet hoa hoc", "vay nhanh ngan ly thuyet hoa hoc", "vay khac gan ly thuyet hoa hoc", "vay khach ngan ly thuyet va hoc", "vay khach ngan ly huyet hoc hoc", "vay khach nganh ky thuyet hoa hoc", "vay khach ngan hay thuyet hoa hoc", "vay khach ngan lan thuyet hoa hoc"
"su sach hanh ky thuat te hoc" » "su sach danh ky thuat te hoc", "su sach han ky thuat te hoc", "su sac hanh ky thuat te hoc", "su sach hanh ky thuat tu hoc", "su sach hanh ky thuat de hoc", "su sach hanh ky thuat he hoc", "so sach hanh ky thuat te hoc", "vu sach hanh ky thuat te hoc", "su sach hanh kem thuat te hoc"

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: (("vay khach ngan ly thuyet hoa hoc") or ("su sach hanh ky thuat te hoc"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("vay khach ngan ly thuyet hoa hoc") OR ("su sach hanh ky thuat te hoc")).
• Removing quotes may allow a broader search: (( vay khach ngan ly thuyet hoa hoc ) or ( su sach hanh ky thuat te hoc )).
• Adding a wildcard symbol may retrieve word variants: (("vay khach ngan ly thuyet hoa hoc") or ("su sach hanh ky thuat te hoc"))*.