[texhax] Semi-bold font looking like MWE font

[Bob Tennent]

 >|Many thanks for that.
 >|But I want to keep the "full bold" of the original font for my headers.
 >|How can I control the useage?

\documentclass{book} %
\usepackage[T1]{fontenc} 
\usepackage{libertine}
\DeclareTextFontCommand{\textsb}{\fontseries{sb}\selectfont}
\begin{document}

\noindent This is normal text.\vspace{3pt}

\noindent \textit{This is normal text in italics} - not strong enough to use for emphasis.\vspace{3pt}

\noindent \textsb{This is semibold text}\vspace{3pt}

\noindent \textbf{This is bold text}\vspace{3pt}

\end{document}

 >|-----Original Message-----
 >|From: Bob Tennent [mailto:rdt at cs.queensu.ca]
 >|Sent: 06 November 2015 02:54
 >|To: Dr A K Hannaby
 >|Subject: Re: [texhax] Semi-bold font looking like MWE font
 >|
 >| >|Does anyone know of a font-family that does not clash  >|with the
 >| font in
 >|the MWE, that supports semi-bold?
 >|
 >|Libertine. BTW, here is what a *Minimal* Working Example looks like:
 >|
 >|  \documentclass{book} %
 >|  \usepackage[T1]{fontenc}
 >|  \usepackage[sb]{libertine}
 >|  \begin{document}
 >|  \noindent This is normal text.\vspace{3pt}
 >|
 >|  \noindent \textit{This is normal text in italics} - not strong enough to
 >|use for emphasis.\vspace{3pt}
 >|
 >|  \noindent \textbf{This is semi-bold text}\vspace{3pt}
 >|
 >|  \end{document}
 >|
 >|Bob T.
 >|