I am using the thebibliography-environment to produce a bibliography for my Latex-file. Iniating the bibliography this way works perfectly fine.
My problem is that I can use any argument for the \cite-command, and it will just be presented in the output in the following manner:
\citedoes not refer to the items of \thebibliography-environment.
This is my preamble:
\documentclass{Vortrag(2)}
\newcommand{\defeq}{\vcentcolon=}
\newcommand{\eqdef}{=\vcentcolon}
\usepackage[all]{xy}
\usepackage{multirow}
\usepackage{multicol}
\usepackage{paralist}
\usepackage{tabto,array}
\usepackage{dsfont,lipsum}
\usepackage{blkarray}
\usepackage{tikz}
\usepackage{amsmath}
\usepackage{enumitem}
\usepackage{listings}
This is the (I think) relevant part of the Vortrag(2).cls-file:
\NeedsTeXFormat{LaTeX2e}
\ProvidesClass{Vortrag}[2014/11/03 besides page geometry fully set up scrreprt class]
\LoadClass[fontsize=12pt, ngerman, twoside=true, twocolumn=false, DIV=calc]{scrartcl}
\RequirePackage[backend=biber]{biblatex}
\RequirePackage[colorlinks=true,pdfstartview=FitB,bookmarks=false, urlcolor=3, linkcolor=5]{hyperref}
\hypersetup{
colorlinks=true,
linkcolor=5,
linktoc=page, %Optinen: page - name - all
}
\RequirePackage[top=3cm, bottom=3cm, inner=2cm, outer=2cm]{geometry}
\RequirePackage{tocloft}
\setlength{\cftbeforesecskip}{4pt}
\setlength{\cftbeforetoctitleskip}{2.3ex \@plus.2ex}
\setlength{\cftaftertoctitleskip}{2.3ex \@plus.2ex}
\RequirePackage[utf8]{inputenc}
\RequirePackage[ngerman]{babel}
\clubpenalty 10000
\widowpenalty 10000
\setkomafont{captionlabel}{\color{3}\bfseries}
\setcapindent{1em}
\KOMAoption{captions}{tableheading, figuresignature}
\RequirePackage{dsfont, mathtools, amssymb, delarray, graphicx, nicefrac,mathrsfs}
\RequirePackage{xspace}
\RequirePackage[amsmath, thmmarks, hyperref]{ntheorem}
\makeatother
I got the cls-file from a friend and I don't know the meaning of every command.
My aim is to use \cite, such that it produces just a number of cited article/book.

.clsfile loadsbiblatex. Withbiblatexthe bibliography is created semi-automatically.thebibliographyis the fully manual way of creating bibliographies. The two approaches are incompatible: https://tex.stackexchange.com/q/392637/35864, see also https://en.wikibooks.org/wiki/LaTeX/Bibliography_Management – moewe Apr 16 '18 at 16:13biblatexand thethebibliographyenvironment at the same time on the command\cite, which is not given in the other post. If you think that this is not worth keeping my post online, then we can delete it definetly – user153906 Apr 19 '18 at 10:25\usepackage{biblatex},thebibliographyand uses\cite. In fact the advantage of the other post over yours is that it has everything wrapped up in one document (and MWE) while there are only non-compilable snippets here. You should not delete your question, it remains searchable as a duplicate and can provide help for others that way. But I don't think your question needs a separate answer or needs to be kept open. – moewe Apr 19 '18 at 10:47biblatex,thebibliographyand "bold" or "undefined" I didn't find the other question via google and the search function on this site is not really known to yield better results than google. I only found the other question because I knew I had written the answer not too long ago. – moewe Apr 19 '18 at 15:58