APA (7th ed.) Citation

Essen, A. v. d., & Levelt, A. H. M. (1982). Irregular singularities in several variables. American Mathematical Society.

Chicago Style (17th ed.) Citation

Essen, Arno van den, and Antonius Henricus Maria Levelt. Irregular Singularities in Several Variables. Providence, R.I: American Mathematical Society, 1982.

MLA (9th ed.) Citation

Essen, Arno van den, and Antonius Henricus Maria Levelt. Irregular Singularities in Several Variables. American Mathematical Society, 1982.