| Daqingmen : Imperial City Entrance 1900 | Daqingmen : Imperial City Entrance 1750 |
| Imperial City Entrance in Ein Tagebuch in Bildern, published by 1902 | Imperial City Entrance in The Complete Map of Peking, Qianlong Period. |
| http://dsr.nii.ac.jp/toyobunko/La-161/V-1/page/0231.html.en |