To cite glmmTMB in publications use:

  Mollie E. Brooks, Kasper Kristensen, Koen J. van Benthem, Arni
  Magnusson, Casper W. Berg, Anders Nielsen, Hans J. Skaug, Martin
  Maechler and Benjamin M. Bolker (2017). glmmTMB Balances Speed and
  Flexibility Among Packages for Zero-inflated Generalized Linear Mixed
  Modeling. The R Journal, 9(2), 378-400. doi: 10.32614/RJ-2017-066.

A BibTeX entry for LaTeX users is

  @Article{,
    author = {Mollie E. Brooks and Kasper Kristensen and Koen J. {van Benthem} and Arni Magnusson and Casper W. Berg and Anders Nielsen and Hans J. Skaug and Martin Maechler and Benjamin M. Bolker},
    title = {{glmmTMB} Balances Speed and Flexibility Among Packages for Zero-inflated Generalized Linear Mixed Modeling},
    year = {2017},
    journal = {The R Journal},
    doi = {10.32614/RJ-2017-066},
    pages = {378--400},
    volume = {9},
    number = {2},
  }