Partners scheme business strand assesment question

I have to write a 2000 word essay on what I think the 4 key considerations are when starting a business. We were told we could get a pass from just using the slides she has shown us but I was wondering if we have to reference the slides properly or not? I am not quoting them or rewriting them but I am using some of the information but I am unsure how you would reference a powerpoint?

Also how many references would you recommend I had because i want a merit so I am going to do some external reading but I don't have any idea how many references I should use?