Albert Mertz left behind a monumental note work, where about 175 notebooks and booklets with text-, sketch- and pictorial material are known. The material falls into five categories whereof these three:

Diaries (1957-1990)
Studio Books (1964-1980)
Red+Blue Books (1971-1975)

is mostly text and written in Danish. They can be studied at the New Carlsberg Foundation’s “Primary Sources in Danish Art History” here

The last two:  

Book Objects (1957-1972)
Picture and Junk Books (1966-1975)

is picture- and collage based artist books and they can be studied here below.