  Given a string $T$ of length $n$, a substring $u = T[i..j]$ of $T$ is called
a shortest unique substring (SUS) for an interval $[s,t]$ if (a) $u$ occurs
exactly once in $T$, (b) $u$ contains the interval $[s,t]$ (i.e. $i \leq s \leq
t \leq j$), and (c) every substring $v$ of $T$ with $|v| < |u|$ containing
$[s,t]$ occurs at least twice in $T$. Given a query interval $[s, t] \subset
[1, n]$, the interval SUS problem is to output all the SUSs for the interval
$[s,t]$. In this article, we propose a $4n + o(n)$ bits data structure
answering an interval SUS query in output-sensitive $O(\mathit{occ})$ time,
where $\mathit{occ}$ is the number of returned SUSs. Additionally, we focus on
the point SUS problem, which is the interval SUS problem for $s = t$. Here, we
propose a $\lceil (\log_2{3} + 1)n \rceil + o(n)$ bits data structure answering
a point SUS query in the same output-sensitive time. We also propose
space-efficient algorithms for computing the minimal unique substrings of $T$.
