# How to cite a diploma thesis with biblatex/biber?

The citation of a PhD thesis and a master's thesis works fine with phdthesis and mathesis respectively. How can I cite a diploma thesis as "Diploma Thesis"?

The following MWE shows what I tried:

\documentclass[paper=a4,fontsize=12pt]{article}
\usepackage[backend=biber]{biblatex}

\begin{filecontents}{\jobname.bib}
@Thesis{Duck2000a,
author      = {Dagobert Duck},
title       = {Seashells as Currency after the Brexit},
type        = {diplomathesis}, % mathesis and phdthesis work here
institution = {University of Ducktown},
year        = {2019},
}
\end{filecontents}

\nocite{*}

\begin{document}
\printbibliography
\end{document}


It compiles, however the string diplomathesis was not substituted by the correct localized string but printed raw instead.

Define a new bibstring diplomathesis and give it a useful replacement text

\documentclass[paper=a4,fontsize=12pt]{article}
\usepackage[backend=biber]{biblatex}

\NewBibliographyString{diplomathesis}
\DefineBibliographyStrings{english}{
diplomathesis = {diploma thesis},
}

\begin{filecontents}{\jobname.bib}
@Thesis{Duck2000a,
author      = {Dagobert Duck},
title       = {Seashells as Currency after the Brexit},
type        = {diplomathesis}, % mathesis and phdthesis work here
institution = {University of Ducktown},
year        = {2019},
}
\end{filecontents}

\nocite{*}

\begin{document}
\printbibliography
\end{document}


The known strings are

bathesis An expression equivalent to the term ‘Bachelor’s thesis’.

mathesis An expression equivalent to the term ‘Master’s thesis’.

phdthesis The term ‘PhD thesis’, ‘PhD dissertation’, ‘doctoral thesis’, etc.

candthesis An expression equivalent to the term ‘Candidate thesis’. Used for ‘Candidate’ degrees that have no clear equivalent to the Master’s or doctoral level.

If it's just a one-off you can also exploit the fact that the type field is printed as literal if there is no bibstring with the appropriate name, so

    type        = {Diploma thesis},


might also work.