Contributing to a digital single market for Europe: barriers and drivers of an EU-wide once-only principleKalvet, Tarmo; Toots, Maarja; Krimmer, Robert Johannesdg.o 18 : Proceedings of the 19th Annual International Conference on Digital Government Research : Governance in the Data Age : Delft, Netherlands, May 30-June 01, 20182018 / Article No. 45, 8 p https://doi.org/10.1145/3209281.3209344 Conference proceedings at Scopus Article at Scopus Article at WOS

Cross-border e-government services in Europe: expected benefits, barriers and drivers of the once-only principleKalvet, Tarmo; Toots, Maarja; Veenstra, Anne Fleur van; Krimmer, Robert JohannesICEGOV2018 : proceedings of the 11th International Conference on Theory and Practice of Electronic Governance : 4 - 6 April 2018, Galway, Ireland2018 / p. 59-68 https://doi.org/10.1145/3209415.3209458 Conference proceedings at Scopus Article at Scopus Article at WOS

Exploring and demonstrating the once-only principle : a European perspectiveKrimmer, Robert Johannes; Kalvet, Tarmo; Toots, Maarja; Cepilovs, Aleksandrs; Tambouris, Efthimiosdg.o 2017 : the proceedings of the 18th Annual International Conference on Digital Government Research : Innovations and Transformations in Government : June 7-9, 2017, Staten Island, NY, USA2017 / p. 546-551 : ill https://doi.org/10.1145/3085228.3085235

How to implement the European digital single market : identifying the catalyst for digital transformationSchmidt, Carsten; Krimmer, Robert JohannesJournal of European Integration2022 / 21 p. : ill https://doi.org/10.1080/07036337.2021.2011267 Journal metrics at Scopus Article at Scopus Journal metrics at WOS Article at WOS

Once only principle : benefits, barriers and next stepsWimmer, Maria A.; Tambouris, Efthimios; Krimmer, Robert Johannes; Gil-Garcia, J. Ramon; Chatfield, Akemi Takeokadg.o 2017 : the proceedings of the 18th Annual International Conference on Digital Government Research : Innovations and Transformations in Government : June 7-9, 2017, Staten Island, NY, USA2017 / p. 602-603 : ill http://dx.doi.org/10.1145/3085228.3085296

Towards a Cross-Border Reference Architecture for the Once-Only Principle in Europe : An Enterprise Modelling ApproachTepandi, Jaak; Grandry, Eric; Fieten, Sander; Draheim, Dirk; Piho, GunnarThe Practice of Enterprise Modeling : 12th IFIP Working Conference, PoEM 2019,Luxembourg, Luxembourg, November 27–29, 2019 : proceedings2019 / p. 103-117 https://doi.org/10.1007/978-3-030-35151-9_7 Conference proceeding at Scopus Article at Scopus Article at WOS

“When need becomes necessity” - The single digital gateway regulation and the once-only principle from a European point of viewSchmidt, Carsten; Krimmer, Robert Johannes; Lampoltshammer, Thomas J.Open Identity Summit 2021: Fachtagung vom 01.-02. Juni 2021 Copenhagen2021 / p. 223-228 https://dl.gi.de/server/api/core/bitstreams/ec03538d-b376-4537-bc0f-aab2936c74f8/content Conference Proceedings at Scopus Article at Scopus