How to reuse complete paper for my thesis? I am currently writing my PhD thesis, and I have published an article together with my supervisor. The third chapter of my PhD thesis (1/3 of my whole thesis) is basically the paper. I plan to include the 30 pages of the article of the content that I have produced almost unchanged, except that it fits to my thesis layout, and I will remake the images, remove the introduction and some other minor changes. I also will add some new content, but this is mostly 3-4 pages.

My first question is, how do you actually cite 30 pages? Do you add a sentence at the beginning of the chapter like that?


  The content of this chapter has been published before in ... 


My second question is, should I ask the "author service" of the journal where my original article has been published if it is okay if I reuse most of the content from the article in my PhD thesis?

There is nothing regarding this issue in my PhD regulations.

[Edit]Some additional information: I am from Germany, I am doing my PhD in math, and I published the article in the journal Numerical Linear Algebra with Applications.
For the first question: When the chapter is really just your paper (reformatted), I would go with what you already suggested; begin the chapter with a small text saying "The content of this chapter has been published in ...".

If it is an extended version, then "The content of this chapter is an extended version of ...".

Regarding the second question: first read the copyright transfer that you signed. Often, it already gives permission for reusing the text and figures in your own thesis. If it does not explicitly state this, or is ambiguous, then it is best to contact the journal.