Institute of Geography
http://www.geo.ut.ee/english/index.html

Science Didactics Department
http://www.ut.ee/biodida/e/index.html

Tallinn Pedagogical University
http://www.tpu.ee/

Ministry of Education
http://www.hm.ee/

School of Exact Sciences of Tartu University
http://www.ttkool.ut.ee/english.html

Avita Publishing House
http://www.avita.ee/catalogue/index.html

Tiger Leap Foundation
http://www.tiigrihype.ee/english/index.html

Nature House
http://www.envir.ee/loodusmaja/english/algus.html

Tartu Nature House
http://www.edu.ee/home/trtlooma/nathouse.htm

Miksike Learning Environment
http://www.miksike.com/

REGIO Ltd.
http://www.regio.ee/index.asp?i=15500326062000836867178&cl=02