Two figures side by side in Tufte-Latex

Question

I'm using Tufte-LaTeX and I have two small figures that I would like to appear side by side. I read this question and answer about putting two figures side by side. I tried this with Tufte-LaTeX, but it only prints the first caption. Also, it would be nice if the captions appeared each under its own figure, like in example I cited. Is there a way to do this? Thanks!

PS

Here is the example I am using

\documentclass[nohyper,titlepage,nols]{tufte-book}

\usepackage{lipsum}
\usepackage{mwe}

\begin{document}
How can I put two figures side-by-side? Not two sub-figures, but two actual
figures
with separate "Fig.: bla bla" captions. A figure is supposed to spread over the
entire text width, but I have two figures which are narrow and long, and I need
to
save the space in order to withstand the pages limit.

\lipsum

\begin{figure}
    \centering
    \begin{minipage}{0.45\textwidth}
        \centering
        \includegraphics[width=0.9\textwidth]{example-image-a} % first figure itself
        \caption{first figure}
    \end{minipage}\hfill
    \begin{minipage}{0.45\textwidth}
        \centering
        \includegraphics[width=0.9\textwidth]{example-image-b} % second figure itself
        \caption{second figure}
    \end{minipage}
\end{figure}

\lipsum[3]

\end{document}

Answer 1

like this?

it seem that simple solution with minipage doesn't work in tufte-book document class (the first caption is lost). however, with \ffigbox is possible to solve your problem, but captions are below figures and not outsides of main text as it is default tufte style:

\documentclass[nohyper,titlepage,nols]{tufte-book}

\usepackage{lipsum}
\usepackage{mwe}

\usepackage{floatrow}   % <--- added



\begin{document}
How can I put two figures side-by-side? Not two sub-figures, but two actual figures with separate "Fig.: bla bla" captions. A figure is supposed to spread over the entire text width, but I have two figures which are narrow and long, and I need to save the space in order to withstand the pages limit.
\begin{figure}[!h]
   \begin{floatrow}
\ffigbox{\includegraphics[width=\linewidth]{example-image-a}}%
        {\caption{first figure}\label{fig:example-1}}
\hfill
\ffigbox{\includegraphics[width=\linewidth]{example-image-b}}%
        {\caption{second figure}\label{fig:example-2}}
   \end{floatrow}
\end{figure}
\lipsum[3]

\end{document}