Guryanov, Igor, Iskander Yarmakeev, Aleksandr Kiselnikov, y Iena Harkova. 2017. «Text Complexity: Periods of Study in Russian Linguistics». Revista Publicando 4 (13 (2). "Quito, Ecuador":616-25. https://revistapublicando.org/revista/index.php/crv/article/view/922.