Book (lem2003sterntagebuecher)
Lem, S.
Sterntageb├╝cher
Suhrkamp, 2003

Book (baeza-yates1999modern)
Baeza-Yates, R. A. & Ribeiro-Neto, B.
Modern Information Retrieval
Addison-Wesley Longman Publishing Co., Inc., 1999