Links and references from this episode:

* Camera obscura

* Wikipedia: Camera obscura (https://en.wikipedia.org/wiki/Camera_obscura)

* Encyclopædia Britannica: Photography (https://www.britannica.com/technology/photography)

* Nicéphore Niépce

* Maison Nicéphor Niépce: The History of Photography (http://www.photo-museum.org/photography-history/)

* Louis-Jacques-Mandé Daguerre

* Mental Floss: Daguerreotype Q&A (http://mentalfloss.com/article/16677/daguerreotype-qa)

* Henry Fox Talbot

* Wikipedia: Calotype (https://en.wikipedia.org/wiki/Calotype)

* Later photography

* Wikipedia: Collodion process (https://en.wikipedia.org/wiki/Collodion_process)

* Smiling in early photographs

* IEEE Transactions on Computational Imaging: A Century of Portraits: A Visual Historical Record of American High School Yearbooks (http://people.eecs.berkeley.edu/~shiry/publications/IEEE_yearbooks.pdf)

* Library of Congress: Her Majesty’s gracious smile. An instantaneous photograph from life (https://www.loc.gov/resource/cph.3b39605/)

* Critical Studies in Media Communication: Why We Say “Cheese”: Producing the Smile in Snapshot Photography (https://www.tandfonline.com/doi/pdf/10.1080/0739318042000331853?needAccess=true)