Sadegh Abbasi Farzin Mokhtarian Josef Kittler Enhancing CSS-based shape retrieval for objects with shallow concavities. 199-211 2000 18 Image Vision Comput. 3 http://dx.doi.org/10.1016/S0262-8856(99)00019-0 db/journals/ivc/ivc18.html#AbbasiMK00