www.hellinger.com/international/english/hellinger_lectures_articles/index.shtml
Bert Hellinger is the founder and key developer of family constellations, which later evolved to be used in organisations.  There are articles on this website that predominantly cover family constellations, and yet are useful information sources on constellations in general.

http://www.systemicfamilysolutions.com/articles.html
This website has a number of articles about constellations.  They mainly focus on family constellations and still have useful information that may be transferred, sometimes with some changes, into the organisational field.

http://www.constellationflow.com/
This is another website with various articles about constellations.  Most are about family constellations, but there is a bit about organisational constellations.

http://www.iskon.it/pages/english_con.html
Iskon, Milan's institute for systemic constellations, is Italy's point of reference for the systemic approach and for solution focused work.

http://www.turninglight.org/constel/prof.html
Darcy Cunningham is one of several people who have gained training Nowhere Foundation and Judith Hemmings about constellations.  Her website covers some basics on constellations.

http://www.stuckbusinessconsulting.com/businessconstellations.htm
Andy Stuck is one of several people who have gained training from Nowhere Foundation and Judith Hemmings about constellations.  Her website covers aspects of constellations.

http://www.tyfrancis.org/resources.html
Ty Francis has been working in this field for a good number of years and has written several articles relating to constellations work

http://www.monkswoodassociates.co.uk/
Helen Harrison is another person who has gained training from Nowhere Foundation and Judith Hemmings about organisational constellations.  Her website has a section which introduces constellations and their place in organisational work.

http://helena-consulting.com.au/organisational_constallation.html
Preeti Helena has a website that covers a variety of aspects associated with constellations.