Penguin Donkey Mark 1, Egon Riss, 1939 .......... 80

Penguin Donkey Mark 2, Ernest Race, 1963 .......... 90

Penguin Donkey Mark 3, Shim and Tomoko Azumi, 2004 .......... 70

* assuming the average width of each book is 1.2cm (e.g. book 73, Decline and Fall by Evelyn Waugh)