I have used BubbleCow for proofreading on several of my horror collections and I have found their service extremely accurate and reliable. They go the extra mile in pointing out subtle problems they find along the way that are very helpful. Sometimes they comment on something funny or appealing such as interesting character names that lift my spirit. They not only propose changes they reference the Chicago Manual Writing Style reason they made it. All you need to do once you receive their output is check yes or no to the proposed change and once you reach the end of the document, your finished. Working with someone who edits hard copy, which forces you to make the changes manually in the end only leaves you with an unedited document. Computerized track changes are imperative. I highly recommend BubbleCow to make an author’s work shine.