The University of Oxford, based in Oxford, England, encompasses humanities, social sciences, medical sciences, and mathematical, physical, and life sciences academic divisions. The institution serves approximately 20,000 students, of whom approximately 12,000 are undergraduates. Continuing education courses are taken by 15,000 people per year. The university offers students 80 degree courses. The University of Oxford provides graduate students with courses that cross traditional disciplinary boundaries. Courses include biomedical engineering, clinical embryology, financial economics, and nanotechnology. The university includes international units. It has offices in New York, Tokyo, and Hong Kong. The Centre for Tropical Medicine conducts research in Kenya, Vietnam, and Thailand. The institution also is known for the Oxford University Press, which publishes dictionaries and other reference works. The university's 100 libraries contain over 11 million printed items. The University of Oxford includes 39 independent and self-governing colleges, including University, Balliol, Merton, St. Catherine's, St. Hilda's, and Nuffield. The institution also includes multiple research units. Isis Innovation Limited, established in 1988, is a technology transfer company that has created over 60 businesses. The University of Oxford also includes Ashmolean, Pitt Rivers, Christ Church Picture Gallery, and other museums.