Courses are organized studies that include at
least a free online textbook and a study guide. Many include exams,
quizzes, instructional videos and other helpful learning resources.
They are suitable for both self-learning and formal instruction.
A short study for serious lifelong learners
A full-length course for serious lifelong learners
These are contemporary textbooks that appear online, free of
charge but with an
undetermined number of pages missing. They are selected for their relevance and