Lassen Compiled Genealogy
Wilhelm Lassen (Wilhelm Theodor Alexander Lassen) began documenting his own family, but soon found it necessary to record information about other families as the nobility intermarried with each other throughout Norway. The result is an extensive collection of pedigrees, descendant charts, etc., which is available on 41 microfilm reels.
In Lassen's Collection (Personal historiske og genealogiske samlinger) there is usually an index at the first of each section listing the families which have been included making most parts of this collection easy to access. Digital images of this collection are now online at Digitalarkivet.
The extracted church books do not contain all of the entries found in the minister's book. For example, the book for Oslo Domkirke, Vår Frelsers menighet, has thirty-six marriage entries for the year 1848. Lassen has extracted only twelve nobility couples. At the time Lassen was compiling his work in the middle decades of the 1800's he was without our modern conveniences of microfilm and internet. He had to borrow the church books or visit the parsonage to have access to the records.
Because he extracted these church books we have access to a portion of the records which were burned or lost. An example of this is the church records from Eidsvoll, Langset, Hurdal and Feiring which were burned in 1877. We now have access to records from 1861, while Lassen made an extraction of christenings, confirmations, marriages, and burials from the Eidsvoll church books for the years 1688 to 1856.
The published volumes contain the same information as the handwritten collection. Lassen began at the beginning of the alphabet with the intention of publishing a few families for each letter of the alphabet. Only a few of the families were ever published and the Family History Library has only volume one of Norske Stamtavler.
It is important to verify information from printed or compiled sources by finding the original whenever possible.
See Wilhelm Lassen's biography (in Norwegian).