Bayer, Rudolf (September 1996). The Universal B-Tree for multidimensional Indexing.{{cite book}}: CS1 maint: date and year (link) https://wwwbayer.in.tum.de/cgi-webcon/webcon/lehrstuhldb/download/39/application/pdf
Markl, V. (1999). "MISTRAL: Processing Relational Queries using a Multidimensional Access Technique". CiteSeerX 10.1.1.32.6487. /wiki/CiteSeerX_(identifier)
Ramsak, Frank; Markl, Volker; Fenk, Robert; Zirkel, Martin; Elhardt, Klaus; Bayer, Rudolf (September 10–14, 2000). Integrating the UB-tree into a Database System Kernel (PDF). 26th International Conference on Very Large Data Bases. pp. 263–272. http://www.vldb.org/conf/2000/P263.pdf
Tropf, H.; Herzog, H. "Multidimensional Range Search in Dynamically Balanced Trees" (PDF). Angewandte Informatik (Applied Informatics) (2/1981): 71–77. ISSN 0013-5704. http://www.vision-tools.com/h-tropf/multidimensionalrangequery.pdf