LANDJEV, I. and T. HONOLD. "Arcs in projective Hjelmslev planes" Discrete Mathematics and Applications, 11.1 (2009): 53-70. Retrieved 21 May. 2013, from doi:10.1515/dma.2001.11.1.53

LANDJEV, I. & HONOLD, T. (2009). Arcs in projective Hjelmslev planes. Discrete Mathematics and Applications, 11(1), pp. 1-103. Retrieved 21 May. 2013, from doi:10.1515/dma.2001.11.1.53

LANDJEV, I. and T. HONOLD. 2009. Arcs in projective Hjelmslev planes. Discrete Mathematics and Applications. 11(1): 1-103. Retrieved 21 May. 2013, from doi:10.1515/dma.2001.11.1.53