Library import error

I've been trying to import additional libraries into the IDE from third party sites relevant to my first project, (including those that support Simon Monk's books) but wherever I go to get them, the import process reports an error like - The library "Programming_Arduino-Master" cannot be used. Library names must contain only basic letters and numbers. (ASCII only and no spaces, and it cannot start with a number). I note that the the file name in the example given in the Arduino site's instructions also contains underscore, so assume that should be OK, although it's not a letter or number, so would that be problematic too?
I've tried renaming the downloaded ZIP file in each case (irrespective of where I get them from, most end in -Master) to remove the hyphen and last word, but this does not appear to make any difference. The manual system also described on the Arduino site only seems to work partially once ALL non alphanumeric characters including underscore have been removed, in that the name appears in the Contributed list after an IDE restart, but in some cases there are no contents, i.e. I can't see any contained sketches. I'm obviously missing something. Any ideas what?