@misc{W2140095548,
  author = {Bernhard Schölkopf and Alexander J. Smola and Klaus‐Robert Müller},
  title = {Nonlinear Component Analysis as a Kernel Eigenvalue Problem},
  year = {1998},
  howpublished = {Neural Computation},
  doi = {https://doi.org/10.1162/089976698300017467}
}