This list is by no means definitive, but these reference and books of critical writing, are ones that I return to time and time again, and are always close to hand.
Photography Changes Everything, Edited by Marvin Heiferman, Aperture, 2012.
Core Curriculum: Essays by Todd Papageorge, Aperture, 2011.
Crisis of The Real: Essays by Andy Grundberg, Aperture, 2010.
Inside the Photograph: Essays by Peter C. Bunnell, Aperture, 2009.
Sun in the Blood of the Cat, Bill Jay, Nazraeli Press, 2001
Letters on Landscape Photography, Henry Peach Robinson, Scovill Manufacturing Company, New York, 1888.
Letters on Landscape Photography by Henry Peach Robinson, Hol Art Books, ebook edition.
Thoughts on Landscape: Collected Writings and Interviews, Frank Gohlke, Hol Art Books, 2009. eBook edition.
Lewis Balz Texts, Lewis Baltz, Steidl, 2012.
Swiss Photobooks from 1927 to the Present: A Different History of Photography, Peter Pfrunder and Sabine Munzenmaier, Lars Muller, 2011.
The Latin American Photobook, Horacio Fernandez, Aperture, 2012.
The Dutch Photobook: A Thematic Selection from 1945 Onwards, Frits Gierstberg and Rik Suermondt, Aperture, 2012.
Believing Is Seeing: Observations on the Mysteries of Photography, Errol Morris, The Penguin Press.
Defiant Images: Photography and Apartheid South Africa, Darren Newbury, Unisa Press.
Martin Parr's Best Books of the Decade: A personal selection, Edited by Moritz Neumüller and Angel Luis González, Photo Ireland.
Eyewitness: Hungarian Photography in the Twentieth Century, Peter Baki, Colin Ford, George Szirtes, Royal Academy of Arts.
Image and Memory: Photography from Latin America, 1866-1994 by Wendy Watriss and Lois Parkinson, University of Texas.
Hans Ulrich Obrist: A Brief History of Curating, JRP Ringier.
Book of 101 Books: The: Seminal Photographic Books of the Twentieth Century by Andrew Roth, Vince Aletti, Richard Benson, May Castleberry, Jeffrey Fraenkel, Daido Moriyama, Shelley Rice, David Levi Strauss, Neville Wakefield; PPP Editions
On Being a Photographer: A Practical Guide by David Hurn, Bill Jay; Lenswork Publishing
The Open Book: A History of the Photographic Book from 1878 to the Present by Andrew Roth; Hasselblad Centre
Blink: 100 Photographers, 10 Curators, 10 Writers; Phaidon
Bill Jay's Album by Bill Jay; Nazraeli Press
Events of the Self: Portraiture and Social Identity. Contemporary African Photography from The Walther Collection. Edited by Okwui Enwezor; Steidl
Looking In: Robert Frank's The Americans by Sarah Greenough, Anne Tucker, Stuart Alexander, Martin Gasser, Jeff Rosenheim, Michel Frizot, Luc Sante, Philip Brookman; Steidl
VU: The Story of a Magazine by Cedric de Veigy and Michel Frizot; Thames & Hudson
The Nature of Photographs by Stephen Shore; Phaidon Press
The Printed Picture by Richard Benson; The Museum of Modern Art, New York
The Disciplinary Frame: Photographic Truths and the Capture of Meaning by John Tagg; University of Minnesota Press
Fotografía Pública: Photography in Print 1919-1939 by Horacio Fernández; Museo Nacional Centro d Arte Reina Sofía
Words Without Pictures by Alex Klein, Charlotte Cotton, James Welling, Kevin Moore, Sharon Lockhart, George Baker, Walead Beshty, Allen Ruppersberg, Shannon Ebner, Jason Evans; Aperture
Crisis of the Real by Andy Grundberg; Aperture
The Mind's Eye: Writings on Photography and Photographers by Henri Cartier-Bresson; Aperture
On Photography by Susan Sontag; Penguin
Japanese Photobooks of the 1960s and 70s by Ivan Vartanian, Ryuichi Kaneko; Aperture
Japan: A Self-Portrait: Photographs 1945 - 1964 by Osam Hiraki, Alain Sayag, Keeichi Takeuchi; Flammarion
Ways of Seeing by John Berger; Penguin
Setting Sun: Writings By Japanese Photographers by Akihiro Hatanaka, Yutaka Kanbayashi, Ivan Vartanian; Aperture
Beauty in Photography: Essays in Defense of Traditional Values by Robert Adams; Aperture
After Photography by Fred Ritchin; W. W. Norton & Co
Why People Photograph by Robert Adams; Aperture
From Adams to Stieglitz: Pioneers of Modern Photography by Nancy Newhall, Beaumont Newhall, Michael E. Hoffman; Aperture
Photography: A Cultural History by Mary Warner Marien; Laurence King
The Ongoing Moment by Geoff Dyer; Abacus
The Photobook: A History Volume 1 & 2 by Martin Parr and Gerry Badger; Phaidon Press
A New History of Photography by Michel Frizot; Koneman UK Limited
Photography's Other Histories by Christopher Pinney; Duke University Press
Street & Studio: An Urban History of Photography by Ute Eskildsen; Tate Publishing
A History of Photography: The Musée d'Orsay Collection 1839-1925: The Musee D'Orsay Collection by Françoise Heilbrun, and Hélène Bocard; Flammarion
A Short History of Photography by Harvey Benge, and Gerry Badger; Dewi Lewis Publishing
The History of Photography: From 1839 to the Present: From 1839 to the Present Day by Beaumont Newhall; The Museum of Modern Art, New York
Revisions: An Alternative History of Photography by Ian Jeffrey; National Museum of Photography, Film & Television
History of Photography in China 1842-1860 by Terry Bennett, Anthony Payne, and Lindsey Stewart; Bernard Quaritch Ltd
Photography: Essays and Images - Illustrated Readings in the History of Photography by Beaumont Newhall; Museum of Modern Art
The Origins of Photography by Helmut Gernsheim; Thames & Hudson
History of Photography: 1685-1914 by Helmut Gernsheim; Harper Collins
Looking at Photographs: 100 Pictures from the Collection of The Museum of Modern Art by John Szarkowski; Museum of Modern Art
Photography: The Key Concepts by David Bate; BERG
Education of a Photographer by Charles H. Traub and Steven Heller; Allworth Press
Photography and Philosophy: Essays on the Pencil of Nature by Scott Walden; Wiley-Blackwell
Photography Degree Zero: Reflections on Roland Barthe’s Camera Lucida by Geofrey Batchen; MIT Press
Focus: The Memoirs of a Life in Photography by Beaumont Newhall; Bulfinch Press
The Daybooks of Edward Weston by Nancy and Beaumont Newhall; Aperture
Seizing the Light: A Social History of Photography by Robert Hirsch; McGraw-Hill Higher Education
Disappearing Witness: Change in Twentieth-Century American Photography by Gretchen Garner; The Johns Hopkins University Press
Modern Photography in Japan 1915-1940 by Ryuichi Kaneko; The Friends of Photography-Carmel
Photography in America: The Formative Years, 1839-1900 - A Documentary History by William Welling; Crowell
The Origins of American Photography: From Daguerreotype to Dry-plate, 1839-1885: The Hallmark Photographic Collection at the Nelson-Atkins Museum of Art by KF Davis; Yale University Press
The Power of Photography: How Photographs Changed Our Lives by Vicki Goldberg; Abbeville Press Inc
Out of the Shadows: Herschel, Talbot and the Invention of Photography by LJ Schaaf; Yale University Press
Snap Judgements: New Positions in Contemporary African Photography by Okwui Enwezor; Steidl
Impressed by Light: British Photographs from paper Negatives, 1840-1860 by Roger Taylor, and Larry J. Schaaf; Yale University Press
Kiosk: A History of Photojournalism 1839-1973 by Robert Lebeck and Bodo von Dewitz; Steidl