The members of this category are administering the university laboratories and they undertake special applied and laboratory teaching work. Special technical laboratory staff: They are responsible of keeping the laboratory equipment in good condition and upgrade it whenever necessary in order to stay up to date. They also provide specific technical laboratory services and help with the laboratory teaching. Administrative staff: This category comprises all employees working in administrative positions. The educational work is also exercised by people that do not belong to the university staff, such as guest professors and generally scientists who are invited to teach specific courses. University units The campus of the Aristotle University covers 230,000 square metres and is located near the centre of the city of Thessaloniki. The majority of the university units is found inside the campus, but there are also various institutions, laboratories, and facilities of the university which are located outside the campus such as the Centre of Byzantine Researches, veterinary clinics, the university farm, and forest reserves. The following are some of the most important university units of the Aristotle University: Library The Aristotle University Library was founded in 1927 and is constituted of two main elements: The Central Library is housed in a separate building at the centre of the university campus; "departmental libraries" are owned by a university department. These two elements comprise the A.U.Th. library system, where more than 800,000 book titles and 300,000 volumes of periodicals can be found. The A.U.Th. library subscribes to 3,500 periodicals from all over the world. The Central Library has a reading room for students and a reading room for university researchers and teaching personnel. The students' reading room has a capacity of approximately 1,300 students and can be used by any student who brings and reads his own books. Every department of the university has its own departmental library where students can find books, periodicals, and information concerning the specific subjects their department deals with. Every departmental library has a reading room whose opening hours are determined according to the needs of the department's students and staff. The Aristotle University Library is nowadays the second largest library in Greece, after the National Library. Since 1976 the library has been a member of International Federation of Library Associations and Institutions (IFLA), which enables it to lend and borrow books from libraries all over the world. Student Club The University Student Club