1. Department of Mathematics & Statistics; South Dakota State University; Brookings SD U.S.A.
2. Department of Applied Marine Science; College of Marine Science and Technology; P. O. Box 170 Massawa Eritrea
3. Prof. Em. Groningen & Leiden University, Zuidlaarderweg 57, Noordlaren; Leiden The Netherlands
4. Marine Research Division; Ministry of Marine Resources; Massawa Eritrea
5. UMR ENTROPIE; Faculty of Science and Technology, Université de la Réunion, CS 92003; 97744 Saint-Denis La Réunion France
6. Laboratoire d'Excellence CORAIL; Perpignan France