Barataud M. 2020. Acoustic Ecology of European Bats: Species, Identification, Study of their Habitats and Foraging Behaviour, Inventaires & biodiversité series. 2nd éd. Biotope éditions, Mèze; MNHN, Paris, 368 pages.

Warning - Be sure to read and fully assimilate the contents of chapters 3 and 4 of the book before you start measuring unidentified signals and comparing the results with the values displayed in the scatter diagrams.
If you neglect this preliminary step you will run a high risk of making mistaken identifications.