The collection of the Sacred Writings at the Baha’i World Center – as of June 2013

…the Research Department… notes that the collection and collation of the Sacred Writings is an ongoing process, and the numbers are continually being revised. The estimates of the numbers of unique works can be given as follows:

• For Bahá’u’lláh, nearly 20,000 unique works have been identified. Most of these Writings have been collected; however, 865 are known to have been revealed, but the texts are not available. Close to 15,000 of the collected works have been authenticated by the Archives Office to date.
• For the Báb, over 2,000 unique works have been identified. Most of these Writings have been collected; however, 74 are known to have been revealed, but the texts are not available. Nearly 1,600 of the collected works have been authenticated.
• For ‘Abdu’l-Bahá, over 30,000 unique works have been identified. All of these Writings have been collected and over 27,000 of them have been authenticated.
• For Shoghi Effendi, over 22,000 unique works have been identified. All of these documents have been collected and the majority of them have been authenticated.

It is estimated that approximately ten per cent of the documents described above are in photocopied form. A fraction of the total numbers of unique works have been published in the original languages or translated into Western languages. However, citing exact numbers would be misleading since much of the unpublished and untranslated material consists of day-to-day correspondence and personal guidance and encouragement, which is less likely to be of general interest. The World Centre is actively pursuing a publication programme for the as yet unpublished major works of the Central Figures of the Faith and Shoghi Effendi. 
- The Universal House of Justice  (From a letter dated 6 June 2013 written by the Department of the Secretariat of the Universal House of Justice to and individual believer)