Öpik, E. (1925). On The Frequency of Proper Motions of Stars, As Derived from The Johannesburg and Helsingfors Blink-Microscope Observations: Appendix. The Luminosity and Density Laws. By E. Öpik. (K. Mattiesen'i trükk).
Chicago Style (17th ed.) CitationÖpik, E. On The Frequency of Proper Motions of Stars, As Derived from The Johannesburg and Helsingfors Blink-Microscope Observations: Appendix. The Luminosity and Density Laws. By E. Öpik. Tartu: (K. Mattiesen'i trükk), 1925.
MLA (9th ed.) CitationÖpik, E. On The Frequency of Proper Motions of Stars, As Derived from The Johannesburg and Helsingfors Blink-Microscope Observations: Appendix. The Luminosity and Density Laws. By E. Öpik. (K. Mattiesen'i trükk), 1925.
Warning: These citations may not always be 100% accurate.