1965 Disneyland Bluebacks

Denver

Does anyone have any info on these cards? How were they distributed? The wax packs I have opened hold only the Puzzleback variety. Would like to know the history of the Bluebacks (handed out at the park, inserts into packs, number produced, etc). There are very few graded on the PSA registry.

Thanks.

Dboneesq

Based on this article, it seems like they were both distributed in the yellow packs.