References
Wikipedia (in English)
https://en.wikipedia.org/wiki/Cold-core_low
https://en.wikipedia.org/wiki/Thermal_wind
https://en.wikipedia.org/wiki/Trough_(meteorology)
Wikipedia (in German):
https://de.wikipedia.org/wiki/Rossby-Welle#Atmosph.C3.A4rische_Rossby-Wellen
https://de.wikipedia.org/wiki/Hochwasser_in_West-_und_Mitteleuropa_2021
https://de.wikipedia.org/wiki/Cut-Off-Prozess
Synoptic textbook:
http://eumetrain.org/synoptic_textbook.html
Cold Core Lows:
https://meteorologyman.wordpress.com/2014/01/09/cold-core-lows/
https://meteorologytraining.tpub.com/14312/css/14312_75.htm
Upper-level low (in German):
http://www.seewetter-kiel.de/seewetter/hoehen_tief.htm
http://www.gerd-pfeffer.de/zirk_tief.html#Hoehentief