Scientific American "Ancient Alignments: A stone circle in Egypt is the world's oldest astronomical observatory" By Alan Hall https://www.scientificamerican.com/article/ancient-alignments/

International University Nature, Society and Man "Great Belt of Megalithic Observatories and Problem of a History of the Pole of the World" By A.M Chechelnitsky https://geolines.ru/eng/publications/HISTORIC-GEODESY/HISTORIC-GEODESY_39.html

https://www.ancient-code.com/ancient-code-ancient-sites-that-align-in-a-nearly-perfect-circle-around-earth/

https://lukeburrage.com/blog/archives/1276