EUACA guidance for carriers and coordinators : Slot usage at airports under the amended EU slot reguation, Summer 2021.
http://preprod.cohor.fr/wp-content/uploads/2021/02/210215-EUACA-guidance-on-EU-Reg-S21.pdf
EU official publication of regulation 2021/250 : EUR-Lex – 32021R0250 – EN – EUR-Lex (europa.eu)