Bella Szwarcman-Czarnota: Z Wilna do Ziemi Izraela. Midrasz (Warsaw), October 2007. p. 48. The article makes clear that Moyshe Kulbak was arrested in September 1937 and executed one month later. Even so, in many encyclopedia articles (similarly to the case of Isaac Babel) 1940 is given as the date of his death.
