Ethiopian Tour Operators Association (ETOA)

here you can find link to Ethiopian Tour Operators Association (ETOA)
http://www.ethioembassy.org.uk/tourism/contents/Tour%20Operators%20in%20Ethiopia.htm

Not all are on that list, as they do not update it regularly

have a look here

http://www.ethtoa.com/new/members_list.html

which is the official website for ETOA