Pyth, 43 42 44 42 bytes

lsm-%R2}hKvMc-ecd\:G\-eK?}\ed}edGYc-rzZd\,

Try it online: Demonstration or Test harness

I think I can still chop one or two bytes.

Explanation

lsm-%R2}hKvMc-ecd\:G\-eK?}\ed}edGYc-rzZd\,  implicit: z = input string
                                    rzZ     convert z to lower-case
                                   -   d    remove all spaces from z
                                  c     \,  and split by ","
  m                                         map each part d to:
               cd\:                           split d by ":"
              e                               and only use the last part (removes page number)
             -     G                          remove all letters (removes odd/even)
            c       \-                        split by "-"
          vM                                  and evaluate all (one or two) numbers
         K                                    and store the result in K
       }hK            eK                      create the list [K[0], K[0]+1, ..., K[-1]]
    %R2                                       apply modulo 2 to each element
   -                                          and remove:
                         }\ed                   "e" in d (1 for in, 0 for not in)
                        ?    }edG               if d[-1] in "abcde...z" else
                                 Y              dummy value
 s                                            combine all the lists
l                                             print the length