The title of the paper is: "Electromagnetic phenomena in a system moving with any velocity smaller than that of light"
It can be found in full here: http://en.wikisource.org/wiki/Electromagnetic_phenomena. Scans of the original are available, at least for the moment, here (pdf) and here (png's). As wikisource notes the work is in the public domain in most territories.
The full citation is listed as:
H. A. Lorentz: Amsterdam Proceedings 12 (1904) 986; Ne´er Sciences Exactes et Naturelles 25 (1882) 363; Proc. Acad.
Science Amsterdam 6 (1904) 809
It is also available as pp. 172-197 of (paywalled)
Collected Papers. Volume V. H. A. Lorentz. (Springer, Netherlands, 1937).