I've been reviewing the calculus I've forgotten years ago, by taking pictures of my old Schaum's study guide with my iPad, and doing the problems while sitting

I've been reviewing the calculus I've forgotten years ago, by taking pictures of my old Schaum's study guide with my iPad, and doing the problems while sitting on public transportation. I find the badly kerned math typography of the Open Stax offering, and the PDF version of the modern Schaum's study guide, to be distractingly jarring.