Parts 0-8 of the course material is written by Matti Luukkainen . The content of part 9 is written by developers from Terveystalo . Part 10 is written by Kalle Ilves . Numerous people have improved and corrected the material both in content and spelling. You can also make improvements to the course material yourself. The course webpage is designed and created by Houston inc , who have also audited the content of the course material. Chinese translation by Zhang Wei