Door knocker - Wikipedia

A Brief History of the Door Knocker

Door knocker From University, Very old

The British Museum in Thirteen Objects – Doorknocker in the Shape of a Lion's Head

File:Lion head door knocker, 2 of 2, Roman, Italy, 1st century BC to 1st century AD, bronze - Spurlock Museum, UIUC - DSC05821.jpg - Wikimedia Commons

The Doorbell Invention and Evolution - Blog post - Bay Cities Lock & Safe

Door - Wikiwand

Zoomorphism - Wikiwand

File:Kołatka Biblioteka Raczyńskich.jpg - Wikipedia

File:Celtic Door Knocker.jpg - Wikipedia

Door knocker - Wikipedia

Knock, knock. – BATH NEWSEUM

File:Knocker.jpg - Wikipedia

File:Vladimir Palace door-knocker.jpg - Wikipedia