Reference to return substitutions is found in:
The provision as it is printed, and everything on Ruleside that turns on it.
An additional permanent concussion substitution occurs when a player who has an actual or suspected concussion is substituted and takes no further part in the match. This substitution does not count as one of the ‘normal' permitted substitutions (or substitution opportunities, where applicable).
Verdicts that turn on it 1
Walk the tree to any of these and this clause is part of the answer.
Questions that ask it 2
Points in a walk where the reader is deciding this provision.
The Laws of the Game are published by The IFAB and quoted here for the purpose of explaining the decisions on this site. Ruleside is not affiliated with The IFAB or FIFA. Every clause of Notes and modifications that Ruleside cites.