A first set of DOIs of the AJ journal have been made available in Simbad.

"The Digital Object Identifier (DOI®) System is for identifying content objects in the digital environment". The main journals available in Simbad have defined DOIs for each paper. Simbad has begun to introduce such article identifiers in the database. They are available for reference queries where a regular bibcode can be used. They are also displayed, when they exist, with a reference.

Currently, about 12000 DOis from the AJ journal from 1886 to 2007 have been entered. New DOis will be stored on a regular basis in the future.