Neb. Rev. Stat. § 25-513.01: Neb. Rev. Stat. § 25-513.01

An unincorporated association may be served by personal, residence, certified mail, or designated delivery service upon an officer or managing agent, or by certified mail or designated delivery service to the association at its usual place of business, or by leaving the process at its usual place of business with an employee of the unincorporated association.