1. Cheng Y, Carson T, Elgindi MBM (2012) A note on the proof of the Perron-Frobenius Theorem
2. Langedijk S (2017) COIN 2017—15th JRC annual training on composite indicators & scoreboards 06-08/11/2017, Ispra (IT)
3. European Project CITYkeys Website (2015) http://www.citykeys-project.eu/citykeys/cities_and_regions/Performance-measurement-framework. Accessed May 2020
4. Iglewicz B, Hoaglin DC (1993) How to detect and handle outliers, vol 16 of ASQC basic references in quality control: statistical techniques. American Society for Quality Control, pp 10–13
5. ISO 37120:2018 Sustainable cities and communities—indicators for city services and quality of life. https://www.iso.org/standard/68498.html