The title is "Assignment . . . . . Black Viking" on the title page, "Assignment" and then "Black Viking" as two lines on the front cover, "Assignment—Black Viking" on the spine.
This may be a later printing. The copyright page says "Copyright (c) 1967 ..." and there's no printing date or number stated. The date for this ISFDB record is the copyright date.
The cover artist is not credited. The cover art is signed but is illegible. It may start with "D." and end in a "y" but a scan of the existing artist that fit this pattern did not find anything that matched well.
May-2008 - The cover image is from Amazon ISBN 0449143937.
