B. J. Lloyd, Graham, M. J. D., Clarke, B. A., and Jones, C. J.,
“Effect of reduced depth, fabric-protected slow sand filters on treated water quality”, in
Advances in slow sand and alternative biological filtration, 1996, pp. P. 233-243 : 7 fig., 6 tab.
B. J. Lloyd, Clarke, B. A., Jones, C. J., and Evans, H. L.,
“Water treatment by multistage filtration utilising gravel prefilters and fabric enhanced slow sand filters”, in
Advances in slow sand and alternative biological filtration, 1996, pp. P. 313-326 : 12 fig., 2 tab.