Research involves more than just looking at records. You have to find them first! There are resources that can help you find the records but sometimes the information about where to find things is just not available. Wally Waits passes along information that he has found regarding Oklahoma's birth records. He wrote about "Oklahoma's Delayed Birth Records" in his Muskogee History & Genealogy Blog: http://muskogeephoenixonline.com/blogs/WallyWaits/2009/08/oklahomas-delayed-birth-records.html
Researchers like Wally help make it alot easier for the rest of us!