Historically there have been differences among investigators regarding the definition of organizational culture. Edgar Schein, a leading researcher in this field, defined "organizational culture" as comprising a number of features, including a shared "pattern of basic assumptions" which group members have acquired over time as they learn to successfully cope with internal and external organizationally relevant problems. Elliott Jaques first introduced the concept of culture in the organizational context in his 1951 book The Changing Culture of a Factory.