Mahillon, J., & Delcour, J. (1984). A Convenient Procedure for the Preparation of Highly Purified Parasporal Crystals of Bacillus-thuringiensis. Journal of Microbiological Methods, 3(2), 69-76. https://doi.org/10.1016/0167-7012(84)90007-1 (Original work published 1984)