%  === Template === EXAMPLE for Sci. Iss. J. Dlugosz Univ. - Mathematics
\documentclass[11pt,twoside]{amsart}
\usepackage{mathtools}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{url}
\usepackage{mathrsfs}% and others but only the used ones
\textwidth 125mm \textheight 190mm

\newcommand{\doi}[1]{DOI \path{http://dx.doi.org/10.16926/m.20xx.yy.#1}}

\title[Short title]{Title of the Article}

\author[F. Author]{{\sl First Author}}

\thanks{$\bullet$ {\sl First author} --- e-mail: {x@yy} \\
\indent Institution}

\author[S. Author]{{\sl Second Author}}

\thanks{$\bullet$ {\sl Second author} --- e-mail: {x@yy} \\
\indent Institution}

\author[T. Author]{{\sl Third Author}}

\thanks{$\bullet$ {\sl Third author} --- e-mail: {x@yy} \\
\indent Institution}

\address{
{\sl First Author}
\newline \indent
University of XXX,
\newline \indent
Institute of Mathematics,
\newline \indent
Address}
\email{first author's e-mail}

\address{
{\sl Second Author} %if applicable
\newline \indent
University of XXX,
\newline \indent
Institute of Mathematics,
\newline \indent
Address}
\email{second author's e-mail}

\address{
{\sl Third Author} %if applicable
\newline \indent
University of XXX,
\newline \indent
Institute of Mathematics,
\newline \indent
Address}
\email{third author's e-mail}

\begin{document}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{flushleft}
\scriptsize {\sc Scientific Issues} \\
Jan D\l{}ugosz University \\
in Cz\k{e}stochowa \\
Mathematics XXX (20XX) \\
XXX--xxx \\
\doi{nn} \\
\hrulefill
\end{flushleft}

\normalsize
% newcommands (only when necessary) for example:
\newtheorem{thm}{Theorem}
\newtheorem{df}{Definition}
\newtheorem{ex}{Example}
\newtheorem{cor}{Corollary}
\newtheorem{lem}{Lemma}
\newtheorem{rem}{Remark}

% ======================

\setcounter{page}{11}
\maketitle
\thispagestyle{empty}
\footnotesize
\section*{Abstract}

Text 

of 

Abstract

\normalsize

% ======================
\section{Introduction}

Text

of 

the 

first 

section

% ======================
\section{Main results}

Text

of 

the 

main 

section(s)


% ======================
\section{Final remarks}

Text 

of 

the 

last 

section

% ======================
\begin{thebibliography}{99}

%Please note:
%we recommend/require providing a Digital Object Identifier (DOI), when it is available.
%DOIs are an attempt to provide stable, long-lasting links for online articles.
%They are unique to their documents and consist of a long alphanumeric code.

%For example:
%Author, A. A., & Author, B. B.
%Title of article. Title of Journal, volume number, page range. Date of publication.
%doi:0000000/000000000000



\bibitem{AczeDhom1} J.~Acz\'el, J.~Dhombres,
\emph{Functional equations in several variables},
Cambridge University Press, 1989.

\bibitem{ChuCha} J.~Chang, J.~Chung,
\emph{Hyers-Ulam stability of trigonometric functional equations},
Commun. Korea Math. Soc. 23 (2008), 567-575.
doi : 10.4134/CKMS.2008.23.4.567

\end{thebibliography}

\phantom{} \hfill Received: May 201X  

\end{document}

% ======================

If you are going to use brackets, then write \left
and/or \right before them, for example:

instead of ( ) write \left( \right)

[ ] ------------ \left[ \right]

{ } ------------ \left\{ \right\}

Please leave all other formatting commands for us!

%
