BibTeX, biblatex and biber ⇒ Citation not shown

[rsmnsu]

Code: Select all

\documentclass[12pt,english]{article}
\usepackage{lscape}
\usepackage[T1]{fontenc}
\usepackage[latin9]{inputenc}
\usepackage{array}
%\usepackage{floata}
\usepackage{multirow}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{graphicx}
\usepackage{esint}
\usepackage{booktabs} %for table
\usepackage{amsmath} %for equations and mathematical symbols
\usepackage{rotating} %for table rotation
\usepackage{lscape}
\usepackage{float} % allow tables to self adjust
\usepackage{morefloats}
\usepackage{booktabs,caption,fixltx2e}
\usepackage[flushleft]{threeparttable}
\usepackage{tabularx}
\usepackage{adjustbox}
%\usepackage{enumerate}
%\usepackage{subfigure}
%\usepackage{float}
\usepackage{subfig}
\usepackage{subfloat}
\usepackage{enumitem}

%\usepackage[authoryear]{natbib}
\usepackage[round]{natbib}
\bibliographystyle{plain}

\usepackage[toc,page]{appendix}
\renewcommand{\cite}{\citeyear}
\newtheorem{theorem}{Theorem}
\newtheorem{corollary}{Corollary}
\newtheorem{assumption}{Assumption}
\newtheorem{definition}{Definition}
\newtheorem{proposition}{Proposition}
\makeatletter
\providecommand{\tabularnewline}{\\}
\usepackage{latexsym}\usepackage{psfrag}\usepackage{multirow}\@ifundefined{definecolor}{\usepackage{color}}{}
\usepackage{colortbl}\usepackage{float}\usepackage{lscape}\usepackage{bm}\usepackage[metapost]{mfpic}
% Tree-saver - if turn this on you lose page numbers
 \setlength{\textwidth}{8.276in}
 \setlength{\textheight}{11.705in}
% Allow 1 in margin on each side and nothing else
 \addtolength{\textwidth}{-2in}
 \addtolength{\textheight}{-2in}
 \setlength{\oddsidemargin}{0pt}
 \setlength{\evensidemargin}{\oddsidemargin}
 \setlength{\topmargin}{0pt}
 \addtolength{\topmargin}{-\headheight}
 \addtolength{\topmargin}{-\headsep}
 \newcommand{\ds}{\displaystyle}
 \newcommand{\bs}{\boldsymbol}
 %\pagenumbering{roman}
 \parindent=0pt
 \parskip=5pt
 \def\@cite#1#2{{#1\if@tempswa , #2\fi}}
 \def\@biblabel#1{}
 \def\ph#1{\phantom{#1}}
 \renewcommand{\baselinestretch}{1.0}
\usepackage{babel}

\bibliographystyle{plain}
\bibliography{paper2}
\end{document}

I am getting this error:

Code: Select all

This is BibTeX, Version 0.99d (TeX Live 2016/Debian) 
Capacity: max_strings=100000, hash_size=100000, hash_prime=85009 
The top-level auxiliary file: main.aux 
The style file: plain.bst Illegal, another \bibstyle command---line 68 of file main.aux : 
\bibstyle : {plain} I'm skipping whatever remains of this command 
Database file #1: paper2.bib 
Repeated entry---line 572 of file paper2.bib : 
@article{billio:2012

Moreover, in places of citations in text I am getting ?

Please help

[Johannes_B]

You have \bibliographystyle{plain} two times in your document, it should be there only once.

Also, you are loading packages twice, you are loading packages and then try to redefine stuff the package provides, and it won't even work because @ is not a letter. Your document will throw a lot of errors.