Paper address books are still popular, even in the digital age. They do not require batteries or charger and can be good for keeping track of any kind of info you need to keep in alphabetical order, as for instance new words in a new language. We once met a ER doctor who used a Moleskine black pocket version as an handy medical vade-mecum, with diseases and medicines listed from A to Z. Have you ever thought about using you address book in a different way?
You can choose between Hard and Soft Cover. The former is available in pocket or large sizes, black or red. The latter is part of the Volant family, available in black, blue, sky blue or dark pink colors in three different sizes: extra small, pocket or large. For professional needs indeed, the Folio Index A4 is the best solution.