The Merchants of the Temple and Avarice both reveal alleged financial impropriety at the Vatican.
The former criticises what it deems to be the lavish apartments of some cardinals and Vatican officials, spanning up to 500 square metres in size, compared to Pope Francis' smaller 50 square metre flat.
It highlights one clergyman, Cardinal Domenico Calcagno, who lives on a country estate outside Rome.
The book also claims that the Vatican has lent out buildings that it owns in Rome at significantly lower prices that they're worth to certain acquaintances.
It also alleges that the bank accounts of the Vatican department which assesses candidates for sainthood were temporarily closed, after it failed to file its expenses despite spending tens of millions of euros.
Avarice claims that a charity supporting a children's hospital in Rome also paid £142,000 towards the renovation of a former Vatican official's apartment.
The book also claims £269,000 worth of money that churches donated in 2013 to help the poor was put into a secret bank account used to pay Vatican expenses.
Pope Francis told the Dutch Straatnieuws magazine: "The church must speak with the truth and also with testimony, the testimony of the poor.
"If a believer speaks about poverty or about the homeless, and leads the life of a pharaoh, this cannot be done.
"And how many priests and bishops have we seen [who are like this]? It's sad to speak of, isn't it?"
The Vatican has not commented on the allegations, but it arrested two former civil servants last week for allegedly releasing confidential information.
The Merchants of the Temple and Avarice praise Pope Francis for trying to change the way they claim the Vatican wrongly uses its money.
