Complex sentence: Show bibles are commonly used in television series; new writers and freelancers are often referred to it when writing scripts for the show to ensure continuity with previous episodes; they're also used by individual writers for books and movies to keep track of details.
Split into simpler sentences: Show bibles are commonly used in television series and are used by writers and freelancers to ensure continuity with previous episodes when writing scripts. Bibles are also used by individual writers for books and movies to keep track of details.