Autor: USSR Post
Título: USSR stamp: Cosmonauts Georgy Dobrovolsky, Vladislav Volkov and Viktor Patsayev. Series: In Memory of Cosmonauts, Who Died During the "Soyuz 11" Space Mission, June 6-30, 1971
Data: 20 de Outubro de 1971
Origem: https://commons.wikimedia.org/wiki/File:The_Soviet_Union_1971_CPA_4060_stamp_(Cosmonauts_Georgy_Dobrovolsky,_Vladislav_Volkov_and_Viktor_Patsayev).jpg
Fonte: https://commons.wikimedia.org/wiki/File:Soyuz_11_crew.jpg
Licença: Domínio Público
29-06-1974