| title | ISBN-13 (ISBN-10) | year of publication |
|---|---|---|
| An Introduction to the Study of Variable Stars: -1915 | 978-1-112-24767-5 (1-112-24767-X) | 2009 |
| Catalogue of Stars Within One Degree of the North Pole and Optical Distortion of the Helsingfors Astro-Photographic Telescope Deduced From Photographic Measures: -1900 | 978-1-112-24561-9 (1-112-24561-8) | 2009 |
C. Ellen · C.F. · Caroline E. · Caroline Ellen · E F.