Diadem Books would like to point out that it is the responsibility of the author to obtain copyright for any materials they use in their books that have been written by another person. You are not allowed to take other author's (or illustrator's) material without their permission.
There is a lot to be said on this subject and if you are in any doubt then do your research first, even contacting your lawyer - rather apply yourself to this issue now before you consider going to print. You need to acquaint yourself with the rules if you feel you may be about to use another author's material.
Generally if the author has been deceased for 70 or more years then their copyright is void, however, there are variations to this rule so try to obtain copyright before going to print. If you are unable to find the copyright holder then please tell us.
The Writers' & Artists' Yearbook has a section on copyright.
You must also consider libel:
If your book is non-fiction and contains real life (names) of individuals / groups then have you changed their names or altered the story to avoid people recognising them?
We ask this since if you have changed individual, group and/or place names/actions to protect their identities then we need to know so that we can add extra disclaimer text into your book.
If you have not changed the names of individuals or group/ actions in your book, then consider if this is necessary - how well do you know the people - will they be offended by what you say? As a good rule of thumb ask anyone you have mentioned if they mind - some people will be delighted, others may not. If in doubt ask. However well intentioned your mention may be, do not assume that a person will be happy to see themselves in print, however well disguised.
You will be acknowledging in our contract that there is no libellous text in your manuscript. Diadem Books do not know if the people or places are real - this is the author's responsibility.