Names in Bibliography with Cyrillic not displayed

Question

I'm trying to include names of institutions written in Cyrillic in the bibliography list, with the following code:

main.tex

\documentclass{article}

\usepackage[T2A]{fontenc}
\usepackage[english,bulgarian]{babel}
\usepackage[utf8x]{inputenc}
\usepackage{graphicx}
\usepackage{apacite}

\begin{document}
    \cite{item:2020}

    \newpage
    \bibliographystyle{apacite}
    \bibliography{resources}
\end{document}

In the resources.bib file there the following:

@article{abstract:2020,
    author  = {И.Иванов, Национална Природоматематическа Гимназия, Софийски Университет "Св. Климент Охридски"},
    title   = {Заглавие},
    journal = {Име},
    year    = {1000},
    volume  = {1},
    number  = {1},
    pages   = {1-2},
} 

Instead of the names of the institutions, i.e. Национална Природоматематическа Гимназия Софийски Университет "Св. Климент Охридски", I get the following:

Question:

What am I doing wrong? Is there a way to correct it?

---

Update:

The solution using biblatex+biber as suggested by @Bernard:

\documentclass{article}

\usepackage[T2A]{fontenc}
\usepackage[english,bulgarian]{babel}
\usepackage[utf8x]{inputenc}
\usepackage{graphicx}
\usepackage[stylename=apa, style=authoryear, backend=biber]{biblatex}
\addbibresource{aparesources.bib}

\begin{document}

   \parencite{abstract:2020}

   \newpage
   \printbibliography

\end{document}

Produces the following error:

---

Software used: Overleaf

Compiler: pdfLaTeX

Answer 1

Name fields like author expect names as input and they expect them to be formatted according to the rules explained in How should I type author names in a bib file?.

In your case that means that names should not include the academic affiliation of the author. The correct input for your entry would be

author  = {И. Иванов},

or

author  = {Иванов, И.},

Multiple authors would be separated with and

author  = {Иванов, И. and А. Антонов},
author  = {И. Иванов and А. Антонов and Фёдор Достоевский},

It is uncommon to include the academic affiliation in the bibliography, so I suggest you just drop the Национална Природоматематическа Гимназия, Софийски Университет "Св. Климент Охридски" bit.

biblatex is not compatible with

\usepackage[utf8]{inputenc}

so I changed that to

\usepackage[utf8]{inputenc}

But note that since April 2018 \usepackage[utf8]{inputenc} has been the LaTeX default, so it need not be given at all. For full Unicode support (especially with fonts) you should be looking into LuaLaTeX or XeLaTeX in which case both inputenc and fontenc should be dropped.

Note that biblatex knows no argument stylename, so stylename=apa, will throw an error, so I removed it. If you need APA style, load biblatex with style=apa, (7th. edition APA style) or style=apa6, (6th. edition APA style) [assuming an up-to-date distribution].

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[T2A]{fontenc}
\usepackage[english,bulgarian]{babel}

\usepackage[style=authoryear, backend=biber]{biblatex}

\begin{filecontents}{\jobname.bib}
@article{abstract:2020,
  author  = {И. Иванов},
  title   = {Заглавие},
  journal = {Име},
  year    = {1000},
  volume  = {1},
  number  = {1},
  pages   = {1-2},
} 
\end{filecontents}
\addbibresource{\jobname.bib}

\begin{document}
  \parencite{abstract:2020}

  \printbibliography
\end{document}

produces