The stationery and the stickers used are this old,

yet their contents are clearly written by a child...

Maybe she used her parent's stuff?

I doubt it...

Both the stickers and the stationery seem to be in perfect condition

It would take a truly committed collector to preserve them this well for this long

I doubt that even their child's pestering could convince them to part with such precious items

Then again, it's always possible she used them without permission

Ah-

A 'time slip"...

Huh?