Tod in der Oper
Volker Borbein & Marie-Claire Lohéac-Wieders
Microcontrollers, Fundamentals and Applications with PIC
Fernando E. Valdes-Perez & Ramon Pallas-Areny
Basic German: A Grammar and Workbook
Anna Miell & Heiner Schenke & Karen Seago
German Wikibook
Various
Fundamentals of Spectrum Analysis
Christoph Rauscher