Mahillon, J., Seurinck, J., Delcour, J., & Zabeau, M. (1987). Cloning and Nucleotide-sequence of Different Iso-is231 Elements and Their Structural Association With the Tn4430 Transposon in Bacillus-thuringiensis. Gene, 51(2-3), 187-196. https://doi.org/10.1016/0378-1119(87)90307-6 (Original work published 1987)