Pre-negotiations over Services - A Framework for Evaluation. - Petco E. Tsvetinov (AI, 2003)

Evaluation of services using a fuzzy analytic hierarchy process. - Ludmil Mikhailov; Petco E. Tsvetinov (Appl. Soft Comput., 2004)

Fuzzy approach to outsourcing of information technology services. - Ludmil Mikhailov; Petco E. Tsvetinov (SAC, 2005)

Dominance and ranking issues applying interval techniques in pre-negotiations for services. - Petco E. Tsvetinov; Alan Underwood; Taizan Chan (SAC, 2006)