I come across this problem often, I begin reading a book that is part of a series that has 6 books in total and the last 3 have not been published yet, it will be another 4 years until the last book hits the book stands. I wait and I begin reading another book, it turns out this is part of a trilogy and all books are published, I read the first and second book and 'oh look at that, that book is awesome and cannot wait in the TBR pile any longer, must read now'. Now I am reading/waiting for more books in a series while reading books in a series. I am usually good at keeping track but I am looking for something more systematic. 

 

How do you keep track of books in a series? The ones you read, the ones you are waiting to be published, etc...