"His scholarly reputation was such that in 1940 American historian John L. La Monte described his "Geschichte des Königreichs Jerusalem" as "a masterful history which left little to be desired", although it was written in "ponderous German"; La Monte favoured it in comparison to the recently published French history by René Grousset.Although the "Geschichte" is now out of date, Röhricht's other "magnum opus", the "Regesta Regni Hierosolymitani", remains useful to modern crusade historians; it is a collection of over nine hundred charters and other documents issued from the royal chancery of the Kingdom of Jerusalem, which, until edited and published by Röhricht, had remained scattered throughout dozens of other medieval cartularies.