Assertion: planet's discovery | /r/HasProperty | assigned an isbn for books
Facets:
value: for easy reference
type: PURPOSE
value: for books
type: PURPOSE
Source sentences:
text: While there are still plenty of mythological gods and goddesses left, the IAU works diligently to keep track of all the celestial objects being discovered, and thus discoveries are assigned a permanent number, like an ISBN for books, for easy reference.