I am trying to reference equations in latex (I am writing in overleaf) and am using the code as in the official overleaf documentation i.e.

```
\begin{equation}\label{Emc2}
E=mc^2
\end{equation}
Einstein wrote his famous equation \ref{Emc2}, blah blah blah ....
```

However on compiling, the reference just shows as a pure number i.e.

Einstein wrote his famous equation 1, blah blah blah ….

whereas I would like the number reference in parentheses, as it is in most academic papers

Einstein wrote his famous equation (1), blah blah blah ….

I am surprised that I haven't been able to find documentation for this.

EDIT:

As requested, I am putting in more complete source code. I am writing in several files and have a control file:

```
\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{subfiles}
\usepackage{amssymb}
\usepackage{amsmath}
\usepackage{a4wide}
\title{ }
\author{ }
\date{April 2019}
\begin{document}
\maketitle
\subfile{introduction.tex}
\subfile{math.tex}
\subfile{1.tex}
\subfile{2.tex}
\subfile{3.tex}
\subfile{4.tex}
\subfile{5.tex}
\bibliographystyle{unsrt}
\bibliography{ref.bib}
\end{document}
```

And an example of where I am putting in the equation and reference

```
\documentclass[1.tex]{subfiles}
\begin{document}
\section{.....}
..text..
\begin{equation}\label{PLT}
Z(\lambda) = \int_{\mathcal{C_x}} dz g(z) e^{-\frac{f(x)}{\lambda}}
\end{equation}
..text..
iv) The exact value of the integral \eref{PLT} is then given by...
```

Which shows up as

The exact value of the integral PLT is then given by…

Note that when I am compiling, I am doing so from my control file. All of the citations come out fine in squared brackets, and the references work when using \ref, but not when using \eref

## Best Answer

You have two options; either use

`(\ref{..})`

or`\eqref{..}`

as noted out by @marmot in a comment. The latter requires adding`amsmath`

in your preamble.