2020 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/7BC4932CD94887E338B2DA55488DE8C6/S1473550420000129a.pdf/div-class-title-artificial-versus-biological-intelligence-in-the-cosmos-clues-from-a-stochastic-analysis-of-the-drake-equation-div.pdf Academic paper