@article{CG_1991___10-11_147_0,
     author = {Van~der~Laan, Kees},
     title = {Math into {BLUes} : {Sing} your song},
     journal = {Cahiers GUTenberg},
     pages = {147--170},
     publisher = {Association GUTenberg},
     number = {10-11},
     year = {1991},
     language = {en},
     url = {http://archive.numdam.org/item/CG_1991___10-11_147_0/}
}