Marasinghe, M. G. SAS for data analysis [Electronic resource] : intermediate statistical methods / M. G. Marasinghe, W. J. Kennedy. - Electronic text data. - New York, NY : Springer Science+Business Media LLC, 2008. - (Statistics and computing, ISSN 1431-8784). - ISBN 978-0-387-77372-8 : Б. ц.