However, prisons censor materials far beyond these guidelines. Restrictions on the content of materials in prison libraries are imposed by prison authorities such as wardens, administrators, and security personnel, resulting in the infringement on prisoners' right to read. "Both formal and informal processes of censorship occur in the prison, and there is significant variation in which materials are censored from one institution to the next." International institutions United States America has had prison libraries since 1790. The first state prison library was established in 1802. At the beginning of the 19th century prisons were usually operated by the clergy. The purpose of the library was to increase religious devotion and modify behaviour. In many prisons during this time period the library collection consisted only of the Bible and sometimes prayer books. According to Lehmann (2011), "The main purpose of reading was believed to be strengthening of character, religious devotion, and what we today would call behavior modification. By the mid-nineteenth century, penology (the study, theory, and practice of prison management and criminal rehabilitation) had become more scientific, and criminologists claimed that they knew the reasons for criminal behavior and, consequently, how to reform criminals." In 1870, during the Progressive Period and Prison Reform Movement, the Prison Congress began calling for rehabilitation of convicts instead of retribution, and education and rewards for good behaviour. The library was seen as an incentive and only contained items which furthered the reformative goals of the prison. The first manual for prison libraries was published by the American Library Association in 1915. During the Great Depression prison libraries were expanded. With a decline in industrial demands prisoners became idle and restless and libraries were seen as a way to occupy them. In 1930, a manual for prison libraries was published by the American Correctional Association. The library was believed to be wholesome recreation, which also supported education and mental health, and there was great growth in federal prison libraries for the next four decades. State correctional facilities began to see growth in prison libraries in the 1970s when the Library Services and Construction Act was authorized by Congress. In 1974, two Massachusetts cases – Wolf v. McDonnell and Stone v. Boone – mandated that prisons provide on-site libraries, which paved the way for Bounds v. Smith, 430 U.S. 817 (1977). Bounds v. Smith ruled that prisons were required to provide access to people trained in