[1] In addition to banknotes, Salem collects coins, stock bonds, maps, driving licences, manuscripts, and passports.

"[5] His interest in the visual arts is reflected in the design and colour trials in his collection, such as a note for Cyprus featuring Makarios III that did not go into circulation.

[6] Salem's collection is being sold by Spink and Son in London in a series of auctions, the first of which in October 2013 featured his African banknotes, which he had assembled over 25 years.

[1][7][8] His African material included a collection of notes associated with Patrice Lumumba, the first Prime Minister of the Democratic Republic of the Congo, who was known personally to Salem.

His collection of South American banknotes was sold in January 2019, and included a counterfeit 20 peso note marked Banco Nacional de Cuba (F69) produced by the United States government for the failed Bay of Pigs Invasion in 1961.