Publishers
- Conservation Press 1
- Consiglio Nazionale Delle Ricerche 1
- Constable 13
- Constable & Co. Ltd. 26
- Constable and Company Ltd. 20
- Constable Young Books 3
- Constable Young Books Ltd. 1
- Continuum 2
- Conway 2
- Conway Maritime Press 22
- Copernicus 1
- Coppenrath 1
- Coppice Books 1
- Copple House Books 1
- Cordillera Publishing Company 1
- Corgi 1
- Corgi Yearling Books 1
- Cork University Press 3
- Cornell University Press 4
- Cornish Brothers Limited 4
- Cornmarket 1
- Cornstalk Publishing 1
- Cornstalk Publishing Company 1
- Cornwall Books 1
- Cosmopolitan Book Corporation 1
- Costello 1
- Cote D'Or 1
- Coterie Press Limited 4
- Council For British Archaeology 1
- Council Of Museums In Wales 1
- Council On Foreign Relations 1
- Country & Sporting Publications 1
- Country Life 24
- Country Life Limited 16
- Country Life Ltd. 9
- Countryside Books 6
- Courage Books 1
- Courtauld Institute Of Art Gallery 1
- Coventry University Enterprises Ltd. 1
- Coward-McCann Inc. 1
- Cowbridge Record Society 1
- CP Press 2
- Crash Media Group 2
- Crawford Art Gallery 1
- Crawford House Publishing 2
- CRC Press 8
- Crecy 2
- Crecy Books 2
- Crecy Publishing Limited 7
- Creel Press 1
- Crescent Books 1
- Crestline Publishing Co. Inc. 1
- Cricket Books 1
- Croesor Junction Press 1
- Croil 1
- Croner Publications 1
- Croom Helm 8
- Croom Helm Ltd. 2
- Crosby Lockwood 1
- Crosby Lockwood and Son 2
- Crossprint 1
- Crown Publishers 1
- Crown Publishers Inc. 2
- Crowood 2
- Crowswing Books 3
- Crystal Palace Foundation 1
- Csiro Publishing 1
- Cumbrian Railways Association 1
- Cupples & Leon Company 2
- Cushing-Malloy Inc 1
- Cuthell And Martin 1
- CWM Press 1
- Cwmbran Community Council 1
- Cwmni Cymraeg Foyle 1
- Cwmni Urdd Gobaith Cymru 1
- Cwmni Y. Wasg Eglwysig Gymreig 1
- Cyhoeddedig Gan D. O'Brien Owen 1
- Cyhoeddiadau Barddas 3
- Cyhoeddiadau Mei 1
- Cymric Federation Press 1
- D. & W. Gibbs Ltd. 1
- D. Appleton & Company 2
- D. Appleton And Company 3
- D. Bogue 1
- D. Bradford Barton 20
- D. Brown & Sons Limited 30
- D. Lloyd Hughes And Dorothy M. Williams 1
- D. Mortimore 1
- D. Reidel Publishing Company 7
- D. Salesbury Hughes 1
- D. Van Nostrand 3
- D. Van Nostrand Company 1
- D. Wyllie & Son 1
- D.B. Rees 1
- D.Brown & Sons Ltd. 2
- D.C. Thomson & Co Ltd. 66
- D.S. Brewer 1
- D.V. Publications Ltd. 13
- Da Capo Press 2
- Dahne Verlag 1