Publishers
- Mackie & Co. Limited 2
- MacMillan 36
- Macmillan & Co. 24
- Macmillan & Co. Ltd. 96
- Macmillan Children's Books 29
- Macmillan London Limited 10
- Macmillan Of Canada 1
- MacMillan Press 1
- Macmillan Press Ltd 5
- MacMillan Publishers Ltd. 1
- Macmillan Publishing Co. 6
- Macmillan Publishing Co. Inc. 1
- Macmillan, New York 1
- Madison Press Books 1
- Magdalen College 2
- Magna Books 2
- Magna Press 2
- Magnard 1
- Magpie Publishing 2
- Mainline & Maritime Ltd 3
- Mainstream Publishing 3
- Mainstream Publishing Company (Edinburgh) Ltd. 3
- Malcolm Press 1
- Mallard Press 2
- Malta Ornithological Society 1
- Malta University Press 1
- Mamelok Press 2
- Mammoth 3
- Manas Publications 1
- Manchester University Press 11
- Mandeville Publications 1
- Marcel Dekker 4
- Marcus Harris & Lewis Ltd. 5
- Margaret K. Mcelderry Books 1
- Margo 1
- Marine Media Management 1
- Mariner Press 1
- Marion Lloyd Books 1
- Maritime Books 1
- Maritime Publications 1
- Mark + Moody Limited 1
- Mark Booksellers And Distributors (pvt) Ltd 1
- Markosia Enterprises Ltd. 2
- Marlborough College 1
- Marrin Publishing 1
- Marshall Brothers 1
- Marshall Harris & Baldwin Ltd. 1
- Marsilio 1
- Martin Bairstow 3
- Martin Robertson 1
- Martin Secker 2
- Martin Secker & Warburg Ltd. 1
- Martin's Printing Works 1
- Martinus Nijhoff 2
- Marvel Entertainment Group 1
- Massey University Press 1
- Mastercraft Printing 1
- Mastiff Club Of America 1
- Matador 4
- 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 1
- Max Reinhardt 4
- Maxiprint 2
- Mazzoleni 1
- Mbi Publishing 8
- McClanahan Book Company Inc. 1
- McClelland and Stewart Limited 2
- McClure, Phillips & Co. 1
- McCorquodale & Co. 2
- 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 7
- McGraw-Hill Book Company 11
- Mcgraw-Hill Publishing Company Ltd. 2
- McGraw-Hill Ryerson Limited 1
- McLoughlin Bros. 5
- McService 1
- Mechanical Engineering Publications Limited 1
- 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 2
- Mercer University Press 2
- Mercia Books 1
- Mercian Manuals Ltd 1
- Mercury Books 3
- Meresborough Books 1