A search for H I 21 cm absorption toward the highest redshift (z~5.2) radio-loud objects (2007)
Carilli, C.L., Wang, Ran, Van Hoven, M.B., Dwarakanath, K.S., Chengalur, Jayaram N., Wyithe, Stuart
Restricted Access. An open-access version is available at arXiv.org (one of the alternative locations)