VietTUG.org - old forum

id = 948, parent = 939, thread = 923, catid = 26, locked = 0, moved = 0,
userid = kyanh, ip = 222.252.232.83, time = 2006/01/14 (1137235860) ,
subject = Re:hyperbolic geometry, hits = 0, karma = 0+0-,
Đủ thứ về HG, có lẽ là có ích:

URL: http://www.ics.uci.edu/~eppstein/junkyard/hyper.html