Combinatorics: A Very Short Introduction by Robin Wilson, Oxford University Press, Oxford, 2016, xviii + 158 pp., ISBN 978-0-19-872349-3, $11.95 paperback, $7.99 electronic. Infinity: A Very Short Introduction by Ian Stewart, Oxford University Press, Oxford, 2017, xvi + 144 pp., ISBN 978-0-19-875523-4, $11.95 paperback, $7.99 electronic. (15th March 2018) - Hopkins, Brian