Acknowledging Heinlein

Poul Anderson's first future history series was modeled on Robert Heinlein's Future History;

both include a future revolution, longevity and a generation ship;

Anderson's Operation Chaos further develops the premise of Heinlein's Magic, Inc.;

both involve an expedition into Hell;

Rhysling from the Future History visits Anderson's inter-universal inn, the Old Phoenix;

a Puritan in Anderson's A Midsummer Tempest is named after the First Prophet in the Future History.

Thus, we understand that the Rhysling who visits the Old Phoenix is the same person as the Blind Singer of the Spaceways as seen in "The Green Hills of Earth" whereas the Puritan Nehemiah Scudder merely shares his name with Heinlein's First Prophet. These are two different ways to acknowledge Heinlein.