His many popular German language publications include Handbuch der Ägyptischen Königsnamen, 2nd edition (Mainz, 1999) and Chronologie des Pharaonischen Ägypten or "Chronology of the Egyptian Pharaohs," MÄS 46 (Philip von Zabern, Mainz: 1997), which is regarded by academics as one of the best and most comprehensive books on the Chronology of Ancient Egypt and its various Pharaohs. In 1953, he personally inspected and recorded the Nile Quay Texts at Karnak before they were permanently lost or damaged through erosion.
In other words, the document is just a perfectly ordinary stela depicting the king before this trinity of Gods. Beckerath aptly notes that this new evidence casts serious doubt upon the idea that the damaged Sed Jubilee date in Osorkon II's Bubastis Festival Hall should be read as Year 22, rather than Year 30 of this Pharaoh's reign(the latter reading is possible with some restoration of the damaged numeral) as Edward Wente noted in his 1976 JNES review of Kitchen's TIPE book. Beckerath's analysis thus undermined the conventional view that this king celebrated his Sed Jubilee in his 22nd Year and suggests that Osorkon II likely celebrated his first Jubilee Feast in his 30th Year instead. Traditionally, in Egypt, Sed Jubilee Feasts were held on the 30th Year of a king's reign as is evidenced by the practices of other 22nd Dynasty kings such as Osorkon I, Shoshenq III and Shoshenq V.
In another article titled "Zur Datierung des Papyrus Brooklyn 16.205" in GM 140 (1994), pp.15-17, Professor Beckerath argued that "the 49th regnal year of a king referred to in Pap. Brooklyn 16.205 [which] is generally ascribed to Shoshenq III of the 22nd Dynasty" and comes from a mummy bandage from Deir el-Bahari should be dated to Year 49 of the 21st dynasty king Psusennes I instead because "it is unlikely that private persons from Upper Egypt [would] refer to this late year of Shoshenq III." Shoshenq III is known to have lost effective control of Upper Egypt after his 8th Year when Pedubast I, proclaimed himself king here. All mentions of Shoshenq III after his 8th Year in Upper Egypt are associated with the serving High Priest of Amun, Osorkon B. After the 1993 discovery of a new Tanite king named Shoshenq IV who ruled Egypt for a minimum of 10 years in the 13 year interval from Year 39 of Shoshenq III to Year 1 of Pami, Kenneth Kitchen accepted von Beckerath's proposal in the introduction to the latest (1996) edition of his book, 'The Third Intermediate Period of Egypt(c.1100-650 BC).' Kitchen writes that this new royal arrangement (ie: Shoshenq III->Shoshenq IV->Pami) means that "Papyrus Brooklyn 16.205 of a Year 49 followed by a Year 4 must now be attributed to the time of Psusennes I and Amenemope, not to Shoshenq III and Pimay. [ie. Pami] (cf.103, §83 below)" (Kitchen, TIPE 1996, p.xxvi)
Beckerath also advocates the view that Shoshenq II enjoyed an independent reign at Tanis in his book Chronologie des Pharaonischen Ägypten. This view is seconded by Dautzenberg among other scholars.