The first charmed baryon to be discovered was the Λ c. It is not entirely clear when the particle was first observed; there were a number of experiments which published evidence for the state beginning in 1975, but the reported masses were frequently lower than the value now known. Since then, Λ c have been produced and studied at many experiments, notably fixed-target experiments (such as FOCUS and SELEX) and e e B-factories (ARGUS, CLEO, BABAR, and BELLE).