There is a newly published resource that every apologist will want in his library: Heinrich Denzinger's Compendium of Creeds, Definitions, and Declarations on Matters of Faith and Morals. This reference book is a sorely needed English update to one of the richest compendiums of Catholic doctrine ever compiled.
Commonly referred to simply as Denzinger (after the German theologian who published it in 1854) this doctrinal compendium is a single-volume resource that brings together a wealth of doctrinal documents spanning the history of the Catholic Church. It has been expanded over multiple editions, and it now includes the documents of Vatican II and documents published as recently as 2008. Denzinger is such a valuable resource that even the Magisterium cites it. For example, whenever you see a footnote abbreviated "DS" in the Catechism of the Catholic Church, it is a reference to Denzinger.
Denzinger begins with the creeds of the Church and contains documents organized chronologically beginning with Clement I of Rome's Letter to the Corinthians (circa A.D. 96). It also contains an index that allows you to look up doctrinal statements by topic.
One thing English-only speakers will find particularly helpful in this new edition is the updated marginal numbering system. Marginal numbers were introduced in an early edition of Denzinger, and they remained fairly consistent for about the first hundred years. Then, with the publication of the thirty-second edition in 1963, they were drastically reworked. This presented a problem for English speakers whenever subsequent Church documents referenced editions of Denzinger published in 1963 and later because these newer editions had not been translated into English. In fact, this new (forty-third) edition is the first English translation of Denzinger since the long-outdated thirtieth edition of 1957 titled Sources of Catholic Dogma.
To help remedy this problem, a concordance was introduced some time ago to assist in matching up the new marginal numbers with the old ones. So, for example, if you researched a Denzinger citation in the Catechism (which cites the 1965 edition of Denzinger utilizing the new marginal numbers) you would first need to find the new marginal number in the concordance and then cross-reference it with the corresponding old marginal number. This sounds simple enough but, in practice, it was not always easily accomplished, due to Denzinger's radical overhaul in 1963 that widely increased, abridged, or even omitted many earlier texts. Fortunately, this will no longer be a problem when studying modern documents of the Church.
This valuable new resource should be a welcome addition to every apologist's library. I already got my copy... Did you get yours yet?