BIBDs

[N. J. A. Sloane]

Jim,   BIBDS cover a huge range of topics - what do you
really want to know?

there are a lot of necessary conditions on the parameters
that must be satisfied - see for example Marshall Hall Jr, Combinatorial
Theory (Blaisdell)

For a more extensive treatment see the 2-vol book
on Designs by Thomas Beth et al

Beth, Thomas; Jungnickel, Dieter; Lenz, Hanfried Design theory. Vol. II. Second edition. Encyclopedia of Mathematics and its Applications, 78. Cambridge University Press, Cambridge, 1999. pp. i--xxi and 608--1100. ISBN: 0-521-77231-1 05-01 (05B05)

MR1729456 (2000h:05019) Beth, Thomas; Jungnickel, Dieter; Lenz, Hanfried Design theory. Vol. I. Second edition. Encyclopedia of Mathematics and its Applications, 69. Cambridge University Press, Cambridge, 1999. xx+1100 pp. ISBN: 0-521-44432-2 05B05 (20C30


There's not much in the OEIS - the topic is too broad

Neil