Media type: E-Article Title: Do Hard Topics Exist? A Statistical Analysis Contributor: Culpepper, J. Shane [VerfasserIn]; Faggioli, Guglielmo [VerfasserIn]; Ferro, Nicola [VerfasserIn]; Kurland, Oren [VerfasserIn] imprint: 2021 Published in: Italian Information Retrieval Workshop (11. : 2021 : Bari; Online): IIR 2021: 11th Italian Information Retrieval Workshop 2021 ; 2021 Language: English Origination: Footnote: Access State: Open Access