As reported by Censor.NET, the information is provided by family members and friends of Russian soldiers who got killed on duty under unknown circumstances.
The current list published by Open Russia organization includes about 300 names, and, when available, city of birth, date and place of death. Some also include military ranks and military bases of permanent dislocation. The organization said they had started to form the list in November with 227 names, but was subsequently enlarged to 250.
Judging by the list, most of the killed militants come from Moscow (15 people) and Dagestan (11 people) provinces of Russia, though the volunteers stress that some information might by inaccurate.
Other listings include Facebook group "Cargo 200 from Ukraine to Russia" ("Cargo 200" / "Gruz 200" is Russian military designation of a killed in action), Rain TV channel, Cargo200.org and LostIvan.com sites (the latter also publishes information from the killed militants` pages at social networks).