Rare reference edition with an enigmatic historical provenance. • Author: Hendrik Antoon Lorentz (Posthumous edition) • Title: Relativitätstheorie: Vorlesungen über theoretische Physik an der Universität Leiden (Volume IV) • Year: 1929 • Language: German This copy features an important handwritten presentation inscription (over 20 words) on the flyleaf, dated 1929, with a signature yet to be identified (see pictures). As Hendrik Lorentz passed away in 1928, this 1929 dedication was most likely written by one of his eminent physicist colleagues, a successor at Leiden University, or a leading contemporary researcher in the field of relativity. Further graphological and historical research will allow the buyer to uncover the exact and potentially prestigious provenance of this book.