Gawlińska-Nęcek, K., et al. “A Solution-Processable Small-Organic Molecules Containing Carbazole or Phenoxazine Structure As Hole-Transport Materials for Perovskite Solar Cells”. Opto-Electronics Review, vol. 27, no. 2, May 2019, pp. 137-42, doi:10.1016/j.opelre.2019.04.003.