Is Jankel Wiernik considered a real authority on the Holocaust?

Question

I am trying to check out what are presented as facts by the Video One third of the Holocaust. http://www.onethirdoftheholocaust.com This question was raised by chapter 1.

Answer 1

Yankel Wiernik (born 1889) was a Jewish Holocaust survivor from Poland who was an influential figure in the Treblinka extermination camp revolt of 1943. Since Weirnik’s escape he has published his account of his time in the camp its title: ‘A Year in Treblinka' . 'A Year in Treblinka' is the story of Wiernik's experiences in Treblinka where he witnessed the tragic loss of hundreds of thousands of innocent lives. Weirnik also testified in the Eichmann Trial in 1961 and was present at the opening of the Treblinka Memorial in 1964. After the second world war Wiernik immigrated to Sweden before later moving to Israel where in 1972 he died at the age of 83.

http://en.wikipedia.org/wiki/Yankel_Wiernik