Digital subscribers can read the O Scale Railroading December 1970 issue which introduced Atlas to the O scale market. The cover photo featured the Union Pacific F9 and a few of the initial cars (in color no less!) which compliments the artical on page 15. Note that pages 19 and 20 covers European plastic O scale as well.
Be sure and read "from the editor..." on page 4 regarding the future of O scale which also mentions of Atlas' entrance into O. Even the ads and O scale dealer directory are interesting to check out.