@online{
   timsrc,
   author = "Grammig, Joachim",
   title = "Lecture Quantitative Methods in Economics and Business Administration, 21. Lesson",
   publisher = "Universität Tübingen",
   year = "2026",
   month = "Jan",
   day = "12",
   url = "https://timms.uni-tuebingen.de:443/tp/UT_20260112_001_ws2526quantmethwiwi_0001",
   urldate = "2026-02-01"
}