A Fotografia É O Percurso da Luz No Tempo
https://ia600508.us.archive.org/17/items/chimiephotograph00barr_0/chimiephotograph00barr_0.pdf
Outros Tempos
https://ia601303.us.archive.org/20/items/agfabookofphotog00barrrich/agfabookofphotog00barrrich.pdf