is.sagepub.com/cgi/content/abstract/33/4/435 The online version of this article can be found at: Published by: http://www.sagepublications.com On behalf of: Chartered Institute of Library and Information Professionals can be found at:Journal of Information ScienceAdditional services and information for http://jis.sagepub.com/cgi/alertsEmail Alerts: http://jis.sagepub.com/subscriptionsSubscriptions: http://www.sagepub.com/journalsReprints.navReprints: http://www.sagepub.com/journalsPermissions.navPermissions: © 2007 Chartered Institute of Library and Information Professionals. All rights reserved. Not for commercial use or unauthorized distribution. at Nanjing University on October 30, 2007http://jis.sagepub.comDownloaded from