sentences:  The works he composed between 1897 and 1904 are sometimes ascribed to his "psychological" period, resulting mainly from a turbulent marriage with the sculptor Anne Marie Brodersen.Nielsen is especially noted for his six symphonies, his Wind Quintet and his concertos for violin, flute and clarinet.In Denmark, his opera "Maskarade" and many of his songs have become an integral part of the national heritage.