Complex sentence: Regiomontanus wrote under the latinized name of "Ioannes de Monteregio"; the adjectival "Regiomontanus" was first used by Philipp Melanchthon in 1534.
Split into simpler sentences: Regiomontanus wrote under the latinized name of "Ioannes de Monteregio". The adjectival "Regiomontanus" was first used by Philipp Melanchthon in 1534.