I'd like a mini-bibliography on the problem of packings disks of diameter 1 in a 2-by-n rectangle. So far all I've found is problem 211 in "The Inquisitive Problem Solver" (by Vanderlind, Guy, and Larson --- hi, Richard); those authors credit Eugene Luks for passing along the problem, but they don't say who first noticed/proved that you can fit more than 2n disks of unit diameter into a 2-by-n rectangle. In addition to seeking the original source for this paradox, I'd like to know of places that write about it clearly. (Is it somewhere in Gardner's works?) Also, the solution provided by Vanderlind et al. isn't the optimal packing; as was recently discussed in this forum (Bill Gosper being the discussant who comes to mind), one can do better with a pattern that repeats every 6 disks. Is that pattern published somewhere? For that matter, where is that picture? Someone posted a link to it, but Google won't help me find it. Thanks, Jim