I am dealing with data with different units of measurement for NYC neighborhoods and I am trying to build a composite score with it. For example, I have total population by neighborhood, mean income and children as a percentage of the population. Currently, I am just subtracting the mean for each variable, and then dividing it by its standard deviation. These gives me all the data in units of standard deviation. Additionally, one I have standardized the data as described, I subtract to each value in each variable its minimum value, and then I divide it by the different between its maximum and minimum value (max - min value per variable) so that all values run from 0 to 1.
What are good papers or books to understand if what I did is correct?