Reference
Dieter Fiege, Yulin Liao (1996): On the pathways of the "Pola" expeditions. Penilpidia ludwigi (Marenzeller, 1893) (Holothurioidea: Elpidiidae) rediscoveres from the Eastern Mediterranean Sea. In: Deep Sea and Extreme Shallow-water Habitats: Affinities and Adaptations. – Biosystematics and Ecology – 11: 61 - 66.