The story is contained in the three books I noted as references, books written by three of the participants in the expedition. Updates and experiences of the voyage were radioed back to the States and printed in newspaper articles in the New York Times as well as articles prior to and after their return which add more information.
These books and New York Times newspaper articles comprise most all the published information on the Greenland Expedition during which Art Young killed his polar bear, at least all I've been able to uncover.
Young did however publish an account of hunting walrus on the expedition in Field and Stream.
If anyone has new or other information on this subject, I'd really like the source.