You search the book you are looking for, copy the BIB entry (BIB Daten), open BibEdit and select Record->Paste.

It is quite easy to create BibTeX entries for books available at Amazon: Amatex. If you want to design your own style file, you may try the LaTeX package MakeBst, see Changing reference list to another format. A collection of BibTeX style files for various journals can be found at the LaTeX Bibliography Styles Database. You will find other style files on CTAN and some style examples here: Styles distributed with MikTeX and Some other examples. If you want other citation styles, you will find some in your LaTeX tree under. Now insert a citation ( Insert->Citation Reference) and view it ( View->View PDF (pdflatex)).Add your database mythesis.bib and enter the style file plainnat. Now click Insert->List & TOC->BibTeX Reference.Create a document and select Document->Settings->Bibliography and check Natbib.

Once you have installed a reference manager, open it, create some bibliographical entries, and save the file as mythesis.bib.

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