| Author: | Haeckel, Ernst, 1834-1919 |
| Subject: | B, Soul, Religion and science, Evolution, Monism |
| Format: | Electronic text |
| Date issued: | 2013 |
| Language: | English |
| Publisher: | Project Gutenberg, |
| Rights: | Public domain in the USA. |
| Download link: | The Riddle of the Universe at the close of the nineteenth century [electronic resource] / Ernst Haeckel |