. . "Sladen (1889)" . "1889"^^ . . "Sladen, W. P. 1889. Report on the Asteroidea. in: Report on the Scientific Results of the Voyage of H.M.S. Challenger during the years 1873\u20131876. Zoology. 30: 1-893." . . "1889"^^ . . "Sladen (1889)" .