From the Chartered Institute of Editing and Proofreading: https://www.ciep.uk/about/faqs/what-is-copyediting/

Excellent article about hiring an academic copy editor: https://wendybelcher.com/writing-advice/how-to-hire-copyeditor/

From the American Copy Editors Society (ACES): https://aceseditors.org/news/2014/how-fast-can-you-edit-everybody-say-6-pages-per-hour