Minimal superpermutation length $L(5)$

The shortest length of a string that contains each permutation of $5$ symbols as a substring.

Updates

• Upper bound: $153$
  Reference unknown
  [via Superpermutations - Greg Egan]
• 2014 Lower bound: $153$
  Ben Chaffin in 2014
  [via Superpermutations - Greg Egan]