I would like to acquire a copy and wonder if you can provide me with any leads to a source.
Although the Encylopedia is the most inclusive source we have for square dance calls, unfortunately the definitions are often poor quality, especially for the calls used at the challenge levels.
If you're looking for historical calls, Burleson's is a decent resource. A much better book (in my opinion) is Jay King's Glossary, which unfortunately is no longer in print.
For the advanced and challenge levels, there are much better definition books available (including our own Ceder Chest Square Dance Definition books).
You can also download definition sets from the Callerlab website ( http://www.callerlab.org/ ).