"Remembrance".. akadeemia.ee. [zarchiwizowane z tego adresu (2016-04-07)]. Estonian Academy of Sciences Year Book, XII(39), 2006, ISSN 1406-1503, p. 164.
"Remembrance".. akadeemia.ee. [zarchiwizowane z tego adresu (2016-04-07)]. Estonian Academy of Sciences Year Book, XII(39), 2006, ISSN 1406-1503, p. 164.