Physics dissertation: Do I give a reference every time I mention a certain piece of work? I'm currently writing my BSc Physics dissertation and I'm using LaTeX with BibTeX so the format of the references is all correct, but there are a number of other papers that I talk about at several points throughout the paper. When referencing one of these papers do I need to include a reference each time I mention it?

Example:


  Throughout this paper I will adopt values for cosmological parameters
  obtained by the Planck Collaboration [1].


and later on in the paper...


  ... there have been numerous projects attempting to measure features
  of the CMB including the COBE satellite [2], the WMAP [3] and, more
  recently, the Planck Collaboration ([1]?).
Yes indeed. For several reasons: 


people might not read your work sequentially, from page 1 to the end;
people might forget that there was already a citation somewhere;
people don't want to recall all previous citations;
the context is different and people don't assume that the reference is the same.