Sibiriakoff, M. **E.190a.26 Preuve élementaire de la proposition fondamentale
de la théorie des lignes paralléles. [In French and Russian,.|
(St. Petersburg, etc. 1881-84.) 3 pphs. 8°.
These are three pamphlets, dated 1881, 1882, and 1884, with the same title but different text.
-Parallel lines.