Reciprocals of Odd Numbers adding to 1/Historical Note

Theorem

David Wells reports in his Curious and Interesting Numbers of $1986$ that this result was reported by Friend Hans Kierstead, Jr. and Harry Lewis Nelson in Volume $10$ of the Journal of Recreational Mathematics, but no information has so far been found to back this up.

It is reported in the various relevant pages in the On-Line Encyclopedia of Integer Sequences that this set was apparently discovered by S. Yamashita in $1976$, but once more corroborative evidence is hard to come by.