General common knowledge does not normally include patent literature and scientific articles (T 206/83, OJ 1987, 5; T 171/84, OJ 1986, 95; T 307/11, T 1641/11, T 571/12, T 1000/12). By way of exception, however, patent specifications and scientific publications may be considered to be common general knowledge (see T 51/87, OJ 1991, 177; T 892/01; T 26/13; T 2196/15). In T 412/09 the board stated that this is so in particular when a series of patent specifications provides a consistent picture that a particular technical procedure was generally known and belonged to the common general knowledge in the art at the relevant date (see also T 151/05, T 452/05, T 1000/12). Special conditions also prevail when a field of research is so new that the technical knowledge is not yet available in textbooks (see T 51/87, OJ 1991, 177; T 772/89; T 892/01; T 890/02, OJ 2005, 497; T 1347/11). Going back as far as T 206/83 (OJ 1987, 5) it was held that information which could only be obtained after a comprehensive search was not to be regarded as common general knowledge (see also T 654/90, T 924/03). T 1634/15 and T 1540/14 (patent documents not entirely unambiguous) summarised the case law.