Table for the 4 triples with object "1870-12-21" sorted by label

Subject	Predicate
mdb:kok: Bieze, Ties Willems (uit Veendam (NL))	mdb:datum
mdb:matroos: Hek, Jakob Koops (uit Veendam (NL))	mdb:datum
mdb:Mentor (1870-12-21)	mdb:datum
mdb:schipper: Schuring, Wybe Tammes (uit Veendam (NL))	mdb:datum