What are the three sources of a unique and valuable strategic position?

The first source is a situation in which there are few needs of many customers. For example, think of a shoemaking company in older times. The common people would have a need for shoes and the shoes were similar and everyone wore more or less the same shoes. Your planning would be how to fulfill the need of wearing shoes to as many people in your community as possible.

The second is Broad needs of a few customers. When thinking about this, think of a really luxurious hotel or a resort. Aside from the common hotel services of giving you a room and something to eat, it would also include things like spas or fancy pools or could even arrange for you to get a high amount of various special services because you are among the few who can pay. 

The third is fulfilling broad needs of many customers. Think of a phone services providers. They have numerous customers with various needs, someone wants more ability to make phone calls cheaply, others want to text or use the internet more. There are numerous needs and numerous customers and you have to understand this to be successful.