Drivers for and barriers to the cross-border implementation of the once-only principleLeosk, Nele; Põder, Irma; Schmidt, Carsten; Kalvet, Tarmo; Krimmer, Robert JohannesThe once-only principle : The TOOP project2021 / p. 38–60 https://doi.org/10.1007/978-3-030-79851-2_3 Collection metrics at Scopus Article at Scopus Collection metrics at WOS Article at WOS