Thanks. Thanks a lot. You saved my days. Such an easy way, but difficult to find for a new user!!!
Without this I thought to create a new field in all my refarance types, and copy there authors or titles (if there is no author). This would take from me about 2-3 days I think, cause I have many books/articles and 10 reference types, and ofcourse it would be inefficient in terms of info repetition and further management.