If you use YAPS, please cite it as

  Baktoft, H., Gjelland, K. Ø., Økland, F., & Thygesen, U. H. (2017).
  Positioning of aquatic animals based on time-of-arrival and random
  walk models using YAPS (Yet Another Positioning Solver).  Scientific
  Reports, 7(1), 14294. https://doi.org/10.1038/s41598-017-14278-z

A BibTeX entry for LaTeX users is

  @Article{,
    title = {Positioning of aquatic animals based on time-of-arrival and 
random walk models using YAPS (Yet Another Positioning Solver)},
    journal = {Scientific Reports},
    volume = {7},
    number = {1},
    pages = {14294},
    year = {2017},
    doi = {10.1038/s41598-017-14278-z},
    url = {https://www.nature.com/articles/s41598-017-14278-z},
    author = {H. Baktoft and K.Ø. Gjelland and F. Økland and U.H. Thygesen},
  }