The invention provides imidazoacridone compounds of general formula which have cytotoxic and anti-tumor activity. The evaporative cooler apparatus comprises a bottom and a top, where the bottom and the top are identically dimensioned, and where the top and the bottom are interchangeable. By means of speech recognition back end means associated with databases, the comparable speech pattern is compared with corresponding speech patterns of database entries to determine for each of the at least two databases at least that database entry the speech pattern which best matches the comparable speech pattern of the search term.