Citing cases

One thing I do not understand is why when you site a quotation from a case is that why ALL ER it can be Entores Ltd v Miles Far East Corporation Ltd (1955) 2 All ER 493 ,at 495 and when cite a case from QB or Kb it has to be Brinkibon Ltd v Stahag Stahl [1983] 2 AC 34 at p.42. Why is the word P. (page) included in the first one?

One thing I do not understand is why when you site a quotation from a case is that why ALL ER it can be Entores Ltd v Miles Far East Corporation Ltd (1955) 2 All ER 493 ,at 495 and when cite a case from QB or Kb it has to be Brinkibon Ltd v Stahag Stahl [1983] 2 AC 34 at p.42. Why is the word P. (page) included in the first one?

I actually dont think theres a rule about that. is this just what youve seen in textbooks, because the way quotations are cited tend to vary from book to book. i just site it like: Brinkibon Ltd v Stahag Stahl [1983] 2 AC 34 p.42. i put "per Lord Denning" or whoever, in the main text of the essay, and footnote the citation, but i put the case name and date in the main text as well.

One thing I do not understand is why when you site a quotation from a case is that why ALL ER it can be Entores Ltd v Miles Far East Corporation Ltd (1955) 2 All ER 493 ,at 495 and when cite a case from QB or Kb it has to be Brinkibon Ltd v Stahag Stahl [1983] 2 AC 34 at p.42. Why is the word P. (page) included in the first one?