Ultima7 pt2 : Serpent Isle Walkthrough by Adrian Yau - A complete walkthrough for Ultima7 (one of the first)

Ultima VII Part II: Serpent Isle Walkthrough by (Unknown) - There is no name in this walkthrough, but it still is a great walkthrough as well.

Ultima VII Part Two: Serpent Isle/Silver Seed by Glenn E. Brensinger - Here is a pretty good walkthrough for Silver Seed and Serpent Isle.

The Complete Guidebook v1.4 by Dan Simpson - This is by far the most comprehensive and informative walkthrough there is for Serpent Isle and Silver Seed.

Silver Seed Walkthrough by Gary Thompson - A walkthrough for the Silver Seed add-on

Note: I, the webmaster of Chasing Gwenno, did not write any of these walkthroughs.