Text is transcribed from material in the UCSC Special Collection devoted to the Heinlein Archive, of from print material when not found in the Collection.

Notes follow each Heinlein item.

Most of the content has either never been published before or was published in non-genre publications like newspapers.

«Muster Notes» is the U.S. Naval Academy Class of '29 newsletter.

«Entotic» is the Australian pronunciation of «Antarctic» and is an account of the Heinleins' trip there.

The ISBN of this volume was also assigned to a later one in the series: The Heinlein Letters: Volume III.