After more searching on Amazon, I found Practical Astronomy with your Calculator or Spreadsheet by Peter Duffett-Smith and Jonathan Zwart. This will be my guide on my journey to create the Astronomy Calculator. The fourth edition was published in 2011 so it is current. It also had a website where you can download the Excel spreadsheet with will greatly help in understanding the formulas and testing my website.
So, I now have all the books I need and finally time to start learning about the formulas and translating them into web programming. This journey begins….