FIH Rules of hockey:
FIH Rules of Hockey 2009.pdf


FIH Umpire Briefings
FIH Umpires Briefing 2009.pdf


FIH Umpire Briefing PowerPoint
WorldHockey 2009 FIH Umpires Briefing ppt.pps


USA Hockey website with some useful information
http://www.umpirehockey.com/umpirehockey/artman2/publish/


Was that a good tackle? Video clip (USA Hockey website)
http://www.umpirehockey.com/umpirehockey/artman2/publish/Helpful_Videos_16/Was_THAT_a_good_tackle_90.shtml


Harewood Hockey Umpires - A series of papers, written by John Gawley, have been gathered here to assist umpires, players and umpire coaches improve their knowledge and application of umpiring.   http://www.harewood.co.nz/record/umpires/ 


Umpiring signals
http://www.usfieldhockey.com/hockey/signals.pdf

SPARC Practical Officiating - some useful guides with tips and ideas for umpires
http://www.sparc.org.nz/Sport_Development/officials/learning-areas/practical-officiating