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They are every size a shape you can imagine. They cannot be organized other than to put them in a box, or perhaps hanging file system, but there are only about 3" to 4" all folded up. This information certainly belongs on the web, but there should be some regional links, eg CascadeLinks.
3-hole binder format, laid out on 8.5x11" paper, two sided, or more pages if needed. The most impressive newsletter series I have ever seen is TREE CITY USA BULLETIN, for members of The National Arbor Foundation. They even sent you a binder every so often for them.