Where to find concordats

The Vatican points out that the Latin word doesn't necessarily mean "secret — yet it runs its archives as if it did. For more on the Church's troubled relations with the historical record see:
♦  Pope’s claim to temporal power based on 8th-c forgery  
♦  Timely eviction of the Slovak National Memory Institute (2007) 
♦  The Vatican and the Holocaust: A Preliminary Report International Catholic-Jewish Historical Commission (2000) 
♦  Pius XII, concordat negotiator and Holocaust pope: Wartime archives closed

The “C-word” appears to be avoided, as the Church itself implies, because sometimes it’s politically advisable to pretend that a concordat is something else.

Most concordats are written in two languages. The original is generally in the language of the country concerned, with a translation into Italian, the working language of the Vatican. There are both online concordat collections and also printed volumes of concordats

This is an (incomplete) list of Latin American concordats beginning in the later 19th century. The Spanish concordat of 1851 was retained by the American colonies of Spain which later won independence. They wanted to be regarded as successors of the historical and legal obligations of the Spanish crown, so as to retain the right of patronage over the Catholic Church in their territories.