Looking for Reliable SEO article writer for Long Term

Hi, We are looking for reliable SEO article writer who can provide 50-60 articles per month. The writer should be able to write error and plagiarism free articles. MUST DO KEYWORD SEARCH. Content can't be a simple re-write of other sites, We are in need of quality researched, and authoritative articles on the subject of my niches. 1. Article must be 100% self written and unique. 2. Grammar should be excellent. 3. You are a native English speaker or posses English skills at that level. 4. You can write articles that are interesting to read and posses a lot of useful information. 5. You have to provide the Meta Title and Meta Description along with each article based on Google SEO Guidelines. 6. Articles will be approx 500 or more words in length.