Publishers
- Matilda And War Memorial Hospital 1
- Matthaus Publishers 1
- Matthew S. Batham 1
- Matthiesen Fine Art 1
- Max Parrish 6
- Max Parrish And Co Ltd 2
- Max Reinhardt 4
- Maxiprint 2
- Mazzoleni 1
- Mbi Publishing 9
- McClanahan Book Company Inc. 1
- McClelland and Stewart Limited 2
- McClure, Phillips & Co. 1
- McCorquodale & Co. 3
- McCorquodale & Co. Ltd. 2
- McDougall's Educational Co. Ltd. 1
- McFarland & Company, Inc. 3
- McFarlane & Erskine 1
- McGill-Queen's University Press 1
- McGraw-Hill 8
- McGraw-Hill Book Company 11
- Mcgraw-Hill Publishing Company Ltd. 2
- McGraw-Hill Ryerson Limited 1
- McLoughlin Bros. 5
- McService 1
- Meadow Run Press Inc. 1
- Mechanical Engineering Publications Limited 3
- Mecredy, Percy & Co. Ltd. 1
- Meissner & Buch 1
- Meline, Cans Et Compagine 1
- Melrose Books 1
- Melrose Press Ltd. 1
- Menoshire 1
- Mention The War Ltd 1
- Mention The War Ltd. 2
- Mercat Press 1
- Mercatorfonds 3
- Mercer University Press 2
- Mercia Books 1
- Mercian Manuals Ltd 2
- Mercury Books 2
- Meresborough Books 1
- Meridian Publications 1
- Meridian Publishing Co. 1
- Merlin Books Ltd. 4
- Merlin Bookshop 2
- Merlin Unwin Books 7
- Merrell Publishers Limited 3
- Merrimack Publishing Corp. 2
- Merthyr Tydfil and District Naturalists' Society 2
- Merthyr Tydfil Historical Society 3
- Merton Priory Press 1
- Messrs. Stooke And Son 10
- Methuen 13
- Methuen & Co. 4
- Methuen & Co. Ltd. 108
- Methuen Children's Books 26
- Methuen Children's Books Ltd. 7
- Methuen London Ltd 2
- Methuen Walker Books 2
- Metzler & Co. 1
- Michael D. Dobson 1
- Michael Hale 1
- Michael Hardcastle Publications 1
- Michael Imhof Verlag Gmbh & Co. 1
- Michael J. Elsden 1
- Michael Joseph 28
- Michael Joseph Ltd 2
- Michael Moon 2
- Michael Neugebauer Ltd 1
- Michael O'Mara books Limited 3
- Michael Russell 1
- Michael Russell (publishing) Ltd 2
- Michael Sedgwick Memorial Trust 1
- Michael Stanfield Holdings 1
- Michael Stanfield Holdings Ltd. 1
- Midas Books 1
- Middleton Press 9
- Midland 3
- Midland Automobile Club 2
- Midland Counties Publications 2
- Midland Educational Co. Ltd. 1
- Midland Publishing 22
- Midway 1
- Miklo 16
- Milepost 1
- Military Book Society 1
- Military Heritage Press 1
- Miller's 1
- Mills & Boon 2
- Millstream Books 2
- Millwheel Art Press 1
- Milner And Sowerby 1
- Ministry Of Agriculture Of The Republic Of Iraq 1
- Ministry Of Trade And Industry 1
- Miracle 1
- Miss N. Littleton 1
- Missionsbuchhandlung 1
- Missouri Bureau Of Geology And Mines 1
- Mitchell Beazley 5