"Phillip Helbig (undress to reply)"
writes:
The paper

http://adsabs.harvard.edu/abs/1965SvA.....8..854D

starts out "The present paper is a continuation of [1]"

where [1] is "Ya. B. Zel'dovich, Astron. Zh., 41, 19 (1964) [Soviet
Astronomy - AJ, Vol. 8, p. 13", so I'd conclude that is paper I.

-dan