The most famous Elamite scriptures and the ones that ultimately led to its decipherment are the ones found in the trilingual inscriptions of monuments commissioned by the Achaemenid Persian kings. The inscriptions, similar to that of the Rosetta Stone's, were written in three different writing systems. The first was Old Persian, which was deciphered in 1802 by Georg Friedrich Grotefend. The second, Babylonian cuneiform, was deciphered shortly after the Old Persian text. Because Elamite is unlike its neighboring Semitic languages, the script's decipherment was delayed until the 1840s. Even today, lack of sources and comparative materials hinder further research of Elamite.