You can roughly group all genealogical sources into three types: Primary, Secondary and Tertiary.
Secondary source documents are detailed analyses written after the event—sometimes centuries after—based on explicitly cited primary source documents. When I say explicitly cited, I mean that there are footnotes and endnotes. LOTS of them. Pages of them.
I don’t run into secondary sources very frequently: while there are lots of write-ups of family histories, I haven’t encountered many that bother with citations. Of those that do, the footnotes are too sparse to document all the facts.
When I do find secondary sources, my rule of thumb is to spot check the author’s work for several people. Once I feel confident of the quality of the research, I’ll cite the secondary source directly when obtaining the original documents is too difficult.
This is pretty similar to my principles for tertiary sources, which are summaries of family research without supporting citations. The key difference here is that, while I use both secondary and tertiary sources as roadmaps, I’m willing to directly cite a secondary source once I have confidence in the quality of the research.
The threshold, for me, is when it’s obvious to me that the researcher has gone above & beyond what I can accomplish from my living room.
Let me give you an example: “Our Raser Family” by Edward John Raser. My father-in-law handed me a copy of this book when I first started digging into my wife’s ancestry.
This 261-page single-name study of Rasers in the United States has an additional 66 pages of appendices which include full transcriptions of probate files, real estate documents, family bibles, and stories told by his distant cousins; detailed sources of each family photo and illustration presented in the book, and 22 pages of Greek-text end notes. It represents Edward Raser’s life work, condensing sixty-seven years of research into a single, 374-page tome.
I’ve used this book as a roadmap to my wife’s paternal tree, and for every person in it, Edward not only has the standard records I can find on Ancestry, but a bunch of other hard-to-find resources such as century-old letters and family bibles. At this point, I have such high confidence in Edward’s work, I’ll just cite a page in the book if I can’t find a primary source myself.
Where can you find secondary sources? I consistently run into them in two places:
- One is the Daughters of the American Revolution. You can order full lineages from their site, and those include all the citations used in the application. Mind you, the older the application, the lower the standard of proof.
- You can also find them in old genealogy magazines and the like. Ancestry.com has quite a few digitized and indexed.