how to Include bibliography in table of content?

I am trying to include the bibliography in the toc. I tried \addcontentsline but it does not work. I get I need to make it left like abstract and bolded. below is my code. Please give me a minimal effort suggestion because i am new to latex.

\documentclass[pdftex,12pt,a4paper] \usepackage \titleformat<\bfseries\huge> <\huge>\usepackage[top=3cm, bottom=3cm, left=3.5cm, right=3cm] % graphics images \usepackage[pdftex] \usepackage[toc,page] \usepackage % 1.5 line spacing \usepackage \usepackage \usepackage \onehalfspacing % maths symbols \usepackage %\usepackage[math-style = upright] % table package \usepackage % citation style \usepackage[colorlinks=true,linkcolor=blue]% \makeatletter \let\Hy@linktoc\Hy@linktoc@none \makeatother \usepackage[square,sort,comma,numbers] \usepackage %\renewcommand<> \usepackage \usetikzlibrary \usepackage \usepackage[bf,small,tableposition=top] \usepackage \usepackage \usepackage \usepackage \begin % cover %\input \includepdf[pages=1] % abstract \setcounter \pagenumbering \input % acknowledgement \input % table of content \tableofcontents \addcontentsline % list of tables %\listoftables %\addcontentsline % list of figures %\listoffigures %\addcontentsline % intro chapter \cleardoublepage \pagenumbering \input \input \input %\input \input \input \input \input % references %\bibliographystyle \bibliographystyle \bibliography % appendix %\input \end