1. Adobe Systems Incorporated (1990) PostScript language reference manual, 2nd edn. Addison-Wesley, Reading, Massachusetts, p 393
2. Aggarwa J, Cai Q (1997) Human motion analysis: a review. In: Proceedings of IEEE nonrigid and articulated motion workshop, pp 428–440 Au: Pl. check author name in Ref. [2]
3. Agrawala M, Stolte C (2001) Rendering effective route maps: improving usability through generalization. In: Computer graphics: a quarterly report of ACM SIGGRAPH, vol 18, pp 241–250
4. Allen G (1982) The organization of route knowledge, new directions for child development. Child Conceptions Spat Relat 15:31–39
5. Allen G (1999) Cognitive abilities in the service of wayfinding: a functional approach. Prof Geogr 51(1):554–561