$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
7.58
\begin{equation} \begin{gathered}\label{equation:projectively-cofibrant-squares} \xymatrix@C =50pt@R=50pt{ A \ar [r]^-{f_0} \ar [d]^{f_1} & A_0 \ar [d]^{f_1} \\ A_1 \ar [r]^-{f_0} & A_{01} } \end{gathered} \end{equation}