Which musical form provided mertz with a wealth of repertoire?

The Bardenklänge provided Johan Kaspar Mertz with a wealth of repertoire. The Bardenklänge are regarded as Mertz's most significant contribution to the guitar repertoire (a series of character pieces in the mould of Schumann. The Bardenklänge were printed in 15 books. 

The answer is a : varying the size of objects or subjects, so that some are smaller than others and the illusion of depth is created.hope this : )

The term collage was coined by both  georges braque  and  pablo picasso  in the beginning of the 20th century when collage became a distinctive part of modern art.hope this sorry if there wasn't more of an explanation!