Ésik Zoltán; Fahrenberg Uli; Legay Axel; Quaas Karin: An algebraic approach to energy problems I - continuous Kleene ω-algebras ‡. In: Acta cybernetica, (23) 1. pp. 203-228. (2017)
Ésik Zoltán; Fahrenberg Uli; Legay Axel; Quaas Karin: An algebraic approach to energy problems II - the algebra of energy functions. In: Acta cybernetica, (23) 1. pp. 229-268. (2017)