Dr. Chang graduated from Peking University China and received his PhD in the US. Prior to retirement he managed his own Learning Centre in Canada. This book represents his 40+ years of experience t...view moreDr. Chang graduated from Peking University China and received his PhD in the US. Prior to retirement he managed his own Learning Centre in Canada. This book represents his 40+ years of experience teaching in three countries and epitomizes his teaching style of expressing complex concepts with clarity and ease.view less