When reading some articles about packing puzzles I regularly stumble accros references from the "Journal of Recreational Mathematics" from the 1970s. I did not found any way of accessing these articles, since I cannot even locate the journal. Has anyone an idea how I could get these articles? In particular I am interested in
D. A. Klarner: Brick packing puzzles, J. Recreational Math. 6 (1973), 112-117
J. Haselgrove: Packing a square with Y-pentominoes, J. Recreational Math. 7 (1974), 229
J. Bitner: Tiling 5n x 12 rectangles with Y-pentominoes, J. Recreational Math. 7 (1974), 276-278.