1. Sacral (pelvic) “rib” or coccygeal duplication?;Mares AJ;Z Kinderchir,1981
2. Coccygeal ribs: development and appearance in two cases
3. Sacral rib: a rare congenital anomaly;Rashid M;Acta Orthop Belg,2008
4. Sacrum with five pairs of sacral foramina;Singh R;IJAV,2011
5. A new foramen on posterior aspect of ala of first sacral vertebra;Singh R;IJAV,2012