Principali studiosi di riferimento : Jean Baptiste Lamark

                                                   Carl von Linnč

                                                   Enrico Hillyer Giglioli

                                                   Knipovic

                                                   Alexander Onufrievic Kovalevskij

                                                   Mazzarelli

                                                   Dubois

                                                   Carpenter     

                                                   Karl Friederich Claus