@article {69,
	title = {The interrelationships of echinoderm classes: morphological and molecular evidence},
	journal = {Biological Journal of the Linnean Society},
	volume = {61},
	year = {1997},
	pages = {409{\textendash}438},
	author = {Littlewood, D. T. J. and Smith, A. B. and Clough, K. A. and Emson, R. H.}
}
