The `\textperthousand`

command is available both with the T1 encoding (used by `classicthesis`

) and the TS1 encoding.

However, the Palatino font loaded via the `mathpazo`

package by `classicthesis`

hasn't the required glyph: in the T1 encoding `\textperthousand`

is built by adding a small zero next to `%`

and the small zero is missing (a black square is used to show this).

However the Palatino text companion font has the glyph `\textperthousand`

, so all you need to do is to load `textcomp`

: add

```
\usepackage{textcomp}
```

to your document preamble.

Note that `\textperthousand`

is not legal in math mode and produces a warning. You can avoid it by using

```
\mbox{\textperthousand}
```

or, better, by loading also `amsmath`

and using

```
\text{\textperthousand}
```

You may want to define a variant command that works both in text and math mode:

```
\usepackage{textcomp}
\usepackage{amsmath}
\DeclareRobustCommand{\perthousand}{%
\ifmmode
\text{\textperthousand}%
\else
\textperthousand
\fi}
```

Here, I just scaled the `\square`

in the vertical direction by a factor of 1.5 times the width, and called it `\tallqed`

. The `\smash`

prevents it from affecting line spacing. EDITED to reduce size. Note that first argument of `\scalebox`

is the horizontal scaling, while 2nd (optional) argument is the vertical scaling. These can be adjusted to suit.

```
\documentclass{article}
\usepackage{amssymb,graphicx}
\def\tallqed{\smash{\scalebox{.75}[1.125]{$\square$}}}
\begin{document}
\noindent In view of the choice we made for the orientation of $\partial D$, we conclude that
\[\int_{\partial \mathbf{D}} \iota^*\omega =
(-1)^n \int_{\mathbb{R}^{n-1}} a_n(\cdot,\cdot, \dots, \cdot, 0).\]
This completes the proof of the theorem. \tallqed
\end{document}
```

WChargin correctly points out that the symbol stretch makes the box border thickness non-uniform on the sides compared with the top/bottom. If that is an issue, the problem can be remedied with a slightly altered definition, by `\ooalign`

ing two of the stretched `\square`

s with a slight kern.

```
\documentclass{article}
\usepackage{amssymb,graphicx}
\def\tallqedX{\smash{\scalebox{.75}[1.125]{$\square$}}}
\def\tallqed{\ooalign{\tallqedX\cr\kern.2pt\tallqedX}}
\begin{document}
\noindent In view of the choice we made for the orientation of $\partial D$, we conclude that
\[\int_{\partial \mathbf{D}} \iota^*\omega =
(-1)^n \int_{\mathbb{R}^{n-1}} a_n(\cdot,\cdot, \dots, \cdot, 0).\]
This completes the proof of the theorem. \tallqed
\end{document}
```

## Best Answer

A solution with TikZ: