Enveloping algebra-valued gauge transformations for non-abelian gauge groups on non-commutative spaces B. Jurcǒ, S. Schraml, P. Schupp and J. WessEur. Phys. J. C, 17 3 (2000) 521-526DOI: https://doi.org/epjc/v17/p521(epjc0487)