Publishers
- McFarland & Company, Inc. 3
- McFarlane & Erskine 1
- McGill-Queen's University Press 1
- McGraw-Hill 8
- McGraw-Hill Book Company 13
- Mcgraw-Hill Publishing Company Ltd. 3
- McGraw-Hill Ryerson Limited 1
- McLoughlin Bros. 5
- McService 1
- Mechanical Engineering Publications Limited 5
- Mecredy, Percy & Co. Ltd. 1
- Medallion Press Limited 1
- Meissner & Buch 1
- Meline, Cans Et Compagine 1
- Melrose Books 1
- Melrose Press Ltd. 1
- Menoshire 1
- Mercat Press 1
- Mercatorfonds 1
- Mercer University Press 2
- Mercia Books 1
- Mercian Manuals Ltd 2
- Mercier Press 1
- Mercury Books 2
- Meresborough Books 1
- Meridian Publications 1
- Meridian Publishing Co. 1
- Merlin Books Ltd. 3
- Merlin Bookshop 2
- Merlin Unwin Books 4
- Merrell Holberton Publishers 1
- Merrell Publishers Limited 4
- Merrimack Publishing Corp. 2
- Merthyr Tydfil and District Naturalists' Society 3
- Merthyr Tydfil Historical Society 3
- Merton Priory Press 2
- Messrs. Stooke And Son 12
- Methuen 11
- Methuen & Co. 4
- Methuen & Co. Ltd. 128
- Methuen Children's Books 31
- Methuen Children's Books Ltd. 11
- Methuen London Ltd 1
- Methuen Walker Books 2
- Metropolitan Museum Of Art (Harry & Abrama) 1
- 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 31
- Michael Joseph Ltd 1
- Michael Moon 2
- Michael Neugebauer Ltd 1
- Michael O'Mara books Limited 6
- Michael Russell 1
- Michael Russell (publishing) Ltd 2
- Michael Stanfield Holdings 3
- Michael Stanfield Holdings Ltd. 2
- Mid Glamorgan County Libraries 1
- Middleton Press 12
- Midland 1
- Midland Automobile Club 3
- Midland Bank 1
- Midland Counties Publications 3
- Midland Educational Co. Ltd. 2
- Midland Publishing 28
- Midway 1
- Miklo 17
- Milepost 1
- Military Book Society 2
- Military Heritage Press 1
- Military Mode Publishing 1
- Mills & Boon 2
- Millstream Books 2
- Milner 1
- Milner And Sowerby 1
- Minister Of National Defence 1
- Ministry Of Agriculture Of The Republic Of Iraq 1
- Ministry Of Industry And Primary Resources Brunei 1
- Ministry Of Trade And Industry 1
- Miracle 1
- Miss N. Littleton 1
- Missionsbuchhandlung 1
- Missouri Bureau Of Geology And Mines 1
- Mitchell Beazley 6
- Mitchell Hughes and Clarke 7
- Mitchell Information Services Inc. 1
- Mitsubishi Motors Corporation 1
- Mixing 1
- Model Aeronautical Press Limited 2
- Model And Allied Publications 3
- Modern Promotions 3
- Mondo 1
- Monmouth District Council 1
- Monmouthshire Antiquarian Association 1
- Monnow Press 3
- Monogram Aviation Publications 1
- Montvert Publications 1