There is also often useful information from finding aids in an Archive but you may not have been able to consult the actual record. eg
There were 4 daughters,coheirs to Nicholas Martyns estate. Secondary sources vary considerably as to the husbands of these women.
Ann married Antony Floyer ,Ann married Henry Tichborne, Jane married Antony Floyer, Jane married Henry Tichbourne, Jane married Tristram Dillington
There is a catalogue entry from the Dorset records office for a document concerning the division of the estate between the daughters, from it's date obviously made just before their father's death.
Catalogue reference D-CRI/A/32/3/5
Title Tincleton, manors of Tincleton, Athelhampton etc and other property. Covenant to levy fine. Parties:'1. Nicholas Martyn. 2. Henry Brewen and wife Elizabeth. 3. Thomas White, jun, Fiddleford, and wife Frances. 4. Tristram Dyllyngton, Isle of Wight, and wife Jane. 5. Anne Martyn, youngest daughter of ; (snip) . Bearing eleven seals and signatures. Date 17 Jan 1591
A catalogue entry for a later document in the Devon Archives adds further information mentioning, Ann widow of Antony Floyer and her younger son's William and John, her parents Nicholas Martyn and Margaret and her brother Nicholas Wadham The document was written in the 1st year of Charles 1. So lots more useful supporting genealogical information.
I have seen the first document It didn't really tell me anything more about names and relationships than the catalogue entry had already included ( and very hard to read and manipulate since it is a very large, fragile document. Specialist archivists are better at reading these documents than than me)
I won't be travelling to Devon to see the second one so it should really be a source not consulted. (though you could argue the catalogue entry itself is a source.)