Handbook of Protoctista . Cavalier-Smith T. 1993. The kingdom Protozoa and its 18 phyla. More recent versions have abandoned the tabular format in favor of a narrative description of various classification schemes used in connection with the genus in question, and a summary of the history of these schemes. The principal intent is to help the user find the genus in texts that deal with organismal morphology and taxonomy, and deal with the classification schemes they may find in such sources.
Protistan classification is an active area of research and debate.
As research progresses, phylogenetic concepts change, and the names that are tied to these concepts change as well. Research also discovers numerous instances of wrongly applied labels, such as when two or more species are found hiding under a single species name, and identifies previously undescribed creatures and lineages for which new names are needed. A protist that can be considered either a plant or an animal must therefore have separate names, one for botanists and one for zoologists. Where possible and practical, keys to species are provided. Many of the problems associated with the Classification section also apply here.