Some useful links can be found below:

X-ray interactions with matter	CXRO website
International Union of Crystallography	www.iucr.org
Periodic Table of the Elements	www.webelements.com/index.html
Online ESRF "SPEC" manual	One of many ESRF "SPEC" documentation
Certified Scientific Software	Official "SPEC" website
NPL Multiferroics wiki	Good starting point with Instrumentation and Good Practice guides
ESRF Data Analysis Software	Scientific software list
Other synchrotron sources	Lightsources website