To cite 'NGSSMEL' in publications use:

T. R. d (2020). NGSSEML: Non-Gaussian state space models with exact marginal likelihood package. version 2.1.

Corresponding BibTeX entry:

  @Manual{,
    title = {{NGSSEML}: Non-Gaussian state space models with exact
      marginal likelihood package},
    author = {dos Santos {T. R.}},
    year = {2020},
    note = {version 2.1},
  }