"Summons", "writ of summons", and "complaint filed with the court", would all be possible translations for "atto di citazione", according to page 412 of Vol. 2 of Francesco de Franchis' Dizionario Giuridico. "Summons" is the only translation provided by the Zanichelli/West Law and Commercial Dictionary.
I hope this helps.
Best regards,
Andréa

Questa è la traduzione esatta.

Given the context, I think "complaint" is probably the best answer in this case. "Relata di notifica" would be the "writ of summons". "Cognizione" would be "jurisdiction" or "cognizance".

According to Black's Law Dictionary, a complaint is defined as,"1. The initial pleading that starts a civil action and states the basis for the plaintiff's claim, and the demand for relief. *In some states, this pleading is called a petition. 2. Criminal law. A formal charge accusing a person of an offense."
"Procedimento cautelare", according to de Franchis, is "preventive proceedings", however, he continues in his definition saying "ma si parla più spesso di 'interim injunction' (e, negli S.U., di 'preliminary injunction'), 'restraining order', etc. di solito, una 'motion' comporta l'obbligo della communicazione all'altra parte; ma talune domande, specie in tema di procedimenti cautelari o di urgenza, vengono fatte 'without notice'..."
"Voglia il tribunale..."= "May the Court...establish the legal basis for this complaint..."
I hope this will be more helpful than my first response.
Best regards,
Andréa