Music Copyright QUESTION

Two of my favorite topics are music and copyright law. When they converge, I’m utterly fascinated. Ann from New Zealand wrote about Kookaburra Sits In The Old Gum Tree, a children’s song I learned from a songbook in my elementary school. What I discovered from Ann was that the song was not in the public domain, as I had assumed, but was written in 1934 and is still under copyright. More to the point, the Australian group Men at Work