Complex sentence: His most valuable work was his "Lexicon et commentarius sermonis hebraici et chaldaici" (Leiden, 1669), which has been frequently republished; his theology is fully expounded in his "Summa Doctrinae de Foedere et Testamento Dei" (1648).
Split into simpler sentences: His most valuable work was his "Lexicon et commentarius sermonis hebraici et chaldaici" (Leiden, 1669), which has been frequently republished. His theology is fully expounded in his "Summa Doctrinae de Foedere et Testamento Dei" (1648).