If you are researching ancestors from Hampden County, Hampshire County, Franklin County, or Berkshire County, Massachusetts, take a look at this valuable resource you can access freely at Archive.org. Written in 1855 by Josiah Gilbert Holland, int was published in two volumes.
Volume 1 Parts 1 & 2 [Read]
Volume 2 Part 3 [Read]
Source: History of Western Massachusetts, the Counties of Hampden, Hampshire, Franklin and Berkshire. Embracing an outline, or general history, of the section, an account of its scientific aspects and leading interests, and separate histories of its one hundred towns. Josiah Gilbert Holland, 1855.