Christina Bazzoni uses a band with the book title and author name to create a continuity between these books, allowing her to use very different imagery for every book whilst still keeping a coherant series. The design it's self is strong, however it's a little too dry for my own design tastes and perhaps even those of my target audience.
I really like this series by Jim Tierney. It manages to tie the series together simply by keeping a similar aesthetic through out and using the same decorative font and positions of the author's name. This allows him to play with very different illustrations, appropriate to the individual novels and very different colour schemes even, whilst tying the books together.
This series of Stephen King books by Jamie Keenan has a very strong visual identity, keeping the colour scheme to one colour plus black. Using very similar layout throughout, changing only the imagery and the 'one colour' to make it appropriate to the individual novels. I think they work reasonably well, however the font for the author''s name isn't really to my tatse and I'm not a fan of the way it goes beyond the boundaries of the cover.
Penguin classics (traditional):
I just put these up to show a very simple colour based series. The layouts and the type choices are what keep this working as a series, and I think it works very successfully as a set, however, again, I don't think it's appropriate to my potential target audience.
This series looks amazing. Very simple minimalist layout with different vector art to illustrate the subject of each booklet. I think this is strong but again, might be a little dry in terms of visuals I'm going to look at.
These work because of the same font used throughout and it's desire to use only black and white. Other than that, the covers are very different in terms of layout. Personally, I don't find the designs too pleasing on the eye, although, I can appreciate they are successful and work. I think they're just a bit cold and lifeless for me.
I choe this example to show how books can work in a series through clever packaging. I think the art work for this is beautiful and I really enjoyed how the typography spread across 3 spines, I thought it was very clever. The ilustrations themselves are also beautiful and full of character. I think these are beautifully successful.
I thin that book covers work best as a series if they have 2-3 things in common with each other from the following list: Colour, layout, font, illustration. Too many things in common and oyu have exactly the same book, too few and it doesn't work very coherently.