Perhaps you should try some spelling variations:
"te sach tien chan khoa hoc" » "te sach tren chan khoa hoc", "te sach thieu chan khoa hoc", "te sach thien chanh khoa hoc", "te sach tien thanh khoa hoc", "te sach tien khoan khoa hoc", "te sach tien nhan khoa hoc", "te sach tien chat khoa hoc", "te sach tien han khoa hoc", "te sach tien chan hoa hoc", "toc sach tien chan khoa hoc"
"tu cach xin chai khoa hoc" » "tu cach xin thai khoa hoc", "tu cach xin chi khoa hoc", "tu cach xin pham khoa hoc", "tu cach bien chai khoa hoc", "tu cach kinh chai khoa hoc", "tu cach nhin chai khoa hoc", "tu cach xin chan khoa hoc", "tu cach bia chai khoa hoc", "tu cach lin thai khoa hoc", "tu cach xin chai hoa hoc", "tu cac xin chai khoa hoc"

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("tu cach xin chai khoa hoc") or ("te sach tien chan khoa hoc"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("tu cach xin chai khoa hoc") OR ("te sach tien chan khoa hoc"))*.
• Removing quotes may allow a broader search: (( tu cach xin chai khoa hoc ) or ( te sach tien chan khoa hoc ))*.