(Mostly older) Open Access Monographs in Apocrypha and Pseudepigrapha

C. Tischendorf (ed.), Evangelia apocrypha, 2^nd ed. (Leipzig, 1876) [link]

Das Evangelium des Petrus, ed., tr., nn. T. Zahn (Erlangen and Leipzig, 1893) [link]

C. Taylor, The Oxyrhynchus Logia and the Apocryphal Gospels (Oxford, 1899) [link]

B. Pick, Paralipomena:  Remains of Gospels and Sayings of Christ (Chicago, 1908) [link]

B. Pick (ed., tr.), The Extra-Canonical Life of Christ (New York, 1903) [link]

J. DeQ. Donehoo, The Apocryphal and Legendary Life of Christ (New York, 1903) [link]

Acta apostolorum apocrypha, ed. R. A. Lipsius and M. Bonnet (post C. Tischendorf), vol. 1 (Leipzig, 1891) [link]; vol. 2.1 (Leipzig, 1898) [link]

B. Pick (tr.), The Apocryphal Acts of Paul, Peter, John, Andrew and Thomas (Chicago, 1909) [link]

R. A. Lipsius, Die apokryphen Apostelgeschichten und Apostellegenden: Ein beitrag zur altchristlichen Literaturgeschichte (Braunschweig, 1890) [link]

A. S. Lewis, Apocrypha Syriaca:  The Protevangelium Jacobi and Transitus Mariae (London, 1902) [link]

M. D. Gibson (ed. and tr.), Apocrypha Sinaitica (London, 1896) [link]

R. A. Lipsius, Die Pilatus-Acten kritisch untersucht (Kiel, 1871) [link]

Oracula Sibyllina, ed. J. Geffcken, GCS (Leipzig, 1902) [link]; ed. C. Alexandre, 2^nd ed. (Paris, 1869) [link]; ed. C. Alexandre, vol. 2 [excursus] (Paris, 1854) [link]; ed. J. H. Friedlieb (Leipzig, 1852) [link]

S. C. Malan (ed.), The Book of Adam and Eve:  also Called the Conflict of Adam and Eve with the Serpent, a Book of the Early Eastern Church (London, 1882) [link]

The Psalms of Solomon with the Greek Fragments of the Book of Enoch, ed. H. B. Swete (Cambridge, 1899) [link]

Psalms of Solomon, ed. H. E. Ryle and M. R. James (Cambridge, 1891) [link]

G. P. Luttikhuisen, Gnostic Revisions of Genesis Stories and Early Jesus Traditions (Leiden, 2005) [link - supposedly full text, but some pages missing]

G. R. S. Mead, The Wedding-Song of Wisdom, Echoes from the Gnosis XI (London, 1908) [link]