The textbook "Two-phase queueing systems with N-policy, breakdown and delayed repair" offers a comprehensive analysis of queueing systems that operate with the N-policy. The author, Srinivasa Rao Talagadadeevi, examines the steady-state equations that determine the behavior of these systems. By employing probability generating functions, the steady-state probabilities for various server states are derived. The book also addresses the expected queue length in different server states and determines the expected waiting time in the queue using a heuristic approach. Furthermore, a sensitivity analysis is conducted to identify the optimal threshold of N based on changes in system parameters and cost elements, particularly for the geometric arrival size distribution.