eBay - OK, laugh if you must, but without eBay, the research for this website would have taken much, much longer.  The advantage of eBay has been the volume and variety of viking ship salt cellars that can be found there.  However, there are several points to remember when using eBay as a resource: Information supplied by sellers is not always accurate.  Even the term 'viking ship' is suspect - I've seen clipper ships and oriental boats listed as 'viking ships'.  Viking ships have a single mast, a single sail, and the bow and stern both come to a 'point' (two dragon heads, or one head and one tail, are frequent, but not mandatory).  Viking ship salts don't always have the sail, but don't vary much from the distinct shape (although there are a few exceptions). Pictures can be out of focus or too dark, makers marks can be misidentified, descriptions can be inaccurate.  Some sellers don't even show pictures of the ship or the markings.  One sure way of getting the correct information is to buy the ship, and study and research it yourself.  Effective, but can get expensive! Even without blowing your budget on eBay viking ships, you can still learn from auction listings.  Use photo editing programs to enhance pictures and see details more clearly.  Get to know what to look for; compare to known ships; note differences and similarities.  Verify makers and other marks using on-line or print references. 5,000 Open Salts A Collector's Guide by William Heacock and Patricia Johnson.  Original copyright 1982, reprinted 1995 (and possibly also 1998).  Published by: The Glass Press, Inc. DBA Antique Publications PO Box 553 Marietta, Ohio   45750 1-800-533-3433 ISBN: 1570800154 Two addendums have also been published, 1996-97 Rarity and Price Guide and 2002-03 Rarity and Price Guide.  Although this book contains only 16 different viking ship style salt cellars, it's still a good reference.  The prices and availability information may be somewhat outdated, as internet and online auction sites such as eBay have changed collecting a great deal.  One drawback of H&J is sometimes indistinct pictures, and lack of detailed information, especially on makers marks. Open Salts Info - information about open salt cellars of all kinds, with some good reference links, information about clubs for salt cellar collectors, and more. Online Encyclopedia of Silver Marks, Hallmarks & Maker's Marks - this is an excellent resource, with silver marks from all over the world, and a discussion forum for further research questions.