In using iPhotos Cards, I learnt that I needed to import Aperture Previews into iPhoto 11 to used them. That wasn't a size / storage concern as I was only making a few cards & only used a few images. I have been using Aperture almost exclusively since 2007, have 12k+ images there for my books & slideshows and closed off iPhoto (9.8k images) except for the occasional card, reprint of a book etc.
In making several 2013 calendars in iPhoto11, I would like to utilize many photos from various trips that are now completely in Aperture 3 - Italy, Oregon and other travels and the idea of importing several thousand & having in both libraries seems much but unable to see where I can share Aperture Preview images w/o importing.
Is that a correct assumption?
For a start you need to share details - what version of Aperature and of iPhoto?
If you meet the minimum requirements you can open each library with the other program - which is the easiest solution - http://support.apple.com/kb/HT5260?viewlocale=en_US&locale=en_US