The second edition of the Oxford English Dictionary appeared in 1989, published in 20 volumes.
For the first time there was no attempt to start each volume on letter boundaries, so each volume was roughly equal in size.
The titles of each volume are as follows:
Pity the letters E, G, J, K N, V, X, Y and Z, who fail entirely to make an impression on the twenty spines. But let's all honour S, with its 3 volumes (and no doubt with early appearances in Rob).
The list above offers an Oulipian challenge - perhaps a poem incorporating all twenty words/non words?