LaTeX Warning: Citation undefined

Sample running code:

documentclass[a4paper,11pt]{article}
usepackage[T1]{fontenc}
usepackage[utf8]{inputenc}
usepackage{lmodern}
usepackage[hidelinks]{hyperref} % Hyperref package for url's and [hidelinks] option to remove collouring

title{Test}
author{Thanos}

begin{document}

maketitle
tableofcontents

begin{abstract}
  This is abstract
end{abstract}

section{Section 1}

Referecnce example~cite{ref:thanos}

bibliographystyle{./IEEEtran}
bibliography{./IEEEabrv,./references/ref}

end{document}

It seems like a very simple question/answer but I can not find the error/solution to my problem. I am trying to understand why IEEEtran class is the problem of the code. While I am compiling the current example I keep getting this error:

LaTeX Warning: Citationref:thanos’ on page 1 undefined on input line 21.`

I know that this question has been answered here Undefined citation warnings, which states that the user should compile the code with the following process:

1. latex
2. bibtex
3. latex
4. latex

I tried the following process, but unfortunately, my problem was not solved.

If I change my bibliographystyle{plain} and bibliography{./references/ref} it compiles normally. I have also include the IEEEtran.cls in the same compiling file but unfortunately did help.

Also I tried to compile with LaTeXiLa and a different error is printed:

latexmk -pdf -synctex=1 name.tex
Rule 'bibtex name': File changes, etc:
  Non-existent destination files:
    'name.bbl'
Latexmk: I WON'T RUN 'bibtex configuration' because I don't find the following files:
  ./IEEEabrv.bib
Latexmk: Use the -f option to force complete processing,
 unless error was exceeding maximum runs of latex/pdflatex.
Latexmk: applying rule 'bibtex configuration'...
Latexmk: Errors, so I did not complete making targets

As a next step I deleted all files apart from the .tex file and the reference file, still the same error (terminal and compiler).

The reference sample that I am using:

@online {ref:thanos,
title = {Statistics},
author = {ITU 2014 All Rights Reserved},
titleaddon = {{ITU}},
year = {2014},
month = {Mar.},
urldate = {2014-03-05},
howpublished = {url{http://www.itu.int/en/ITU-D/Statistics/Pages/stat/default.aspx#}}
}

I also tried the format of the reference to @MISC but unfortunately the error is not solved.

I am not 100% sure if I am using biblatex or bibtex, so I am sorry I can not provide more information about it.

Has anybody encounter the same error? I can not find similar information or solution. Thanks in advance for your time and effort.

pdflatex file
bibtex file
pdflatex file
pdflatex file

documentclass[a4paper,11pt]{article}
usepackage[T1]{fontenc}
usepackage[utf8]{inputenc}
usepackage{lmodern}
usepackage[hidelinks]{hyperref} % Hyperref package for url's and [hidelinks] option to remove collouring

title{Test}
author{Thanos}

begin{document}

maketitle
tableofcontents

begin{abstract}
  This is abstract
end{abstract}

section{Section 1}

Referecnce example~cite{ref:thanos}

bibliographystyle{IEEEtran}
bibliography{ref}

end{document}

LaTeX Warning: Citationref:thanos' on page 1 undefined on input line 21.