How wind turbine manufacturer implement Product Service System(PSS) as part of their Product portfolio?

How wind turbine manufacturer implement Product Service System(PSS) as part of their Product portfolio? Order Description Instructions–methodology analysis and finally conclusion.Problem formulation for my project is÷ How wind turbine manufacturer implement Product Service System(PSS) as part of their Product portfolio? for other materials i will pass it later.you can use many internet sources but use at least 3 to 5 books and some really good articles and papers.i need around 45 references(sources)