Aperture file size with referenced files

I am having trouble getting my Aperture file size under control as it seems like many others are in other posts. I have take the actions recommended in other threads. I have used reference files on an external hard drive and also reduced the size of my previews using "half size" in preferences. When I use finder and view package contents on my library file I see folders called Masters, Original, Modified and Previews. Even with the external harddrive disconnected I see large files in the Master and Originals. I see the small files in Previews. I would have expected the data in Masters, Originals and Modified to be stored on the external hard drive to save the space. Am I doing something wrong? Is there some other action I need to take to "recover" the space?

Thanks for any insight you can offer.