Entire collections of the Actae Sanctae Sedis (A.S.S.) and of the Acta Apostolicae Sedis (A.A.S.) - i.e., the official Acts of the Holy See from 1865 to 2007 - are available in pdf format, as is the twelve-volume collection of the Actes et documents du Saint-Siège relatifs à la Seconde Guerre Mondiale, published by order of Paul VI starting in 1965, and edited by a specialised group of four Jesuit historians.These texts represent a documentary resource of inestimable value that is now at the disposal of scholars and all interested persons, free of charge. It is a great contribution to research and information on the history and activities of the Holy See. (Holy See Press Office)
This means that all main acts of the Holy See since 1865, during the Pontificate of Blessed Pius IX, and particularly since 1909, in the Pontificate of Saint Pius X, are now available online. The A.A.S. of 1909, for example, are available here (PDF - large document).