Hamish Henderson's "Songs and Ballads of World War 2" was until recently kept in the "Phi Collection" at the National Library of Scotland. This was a rather miscellaneous selection of material they didn't want the casual public looking at - you needed to use it in the Rare Book Room, and the catalogue was a small notebook rather than the general card index. In most cases the reasons for the categorization was sexual explicitness, but there was one item in the collection I never did figure out. It was published in the 1940s, titled "CuO". It seemed to be a survey of the world market in copper oxide. Maybe it has pornographic annotations. It seems not be in the NLS at all now.