Scherk Minimal Surfaces
In 1835, Heinrich Ferdinand Scherk discovered a pair of complete embedded minimal surfaces; their generalizations are singly and doubly periodic. It is also possible to add handles and edges, as in the last examples.
 M. Weber. "Classical Surfaces." Minimal Surface Archive. (Sep 2013) www.indiana.edu/~minimal/archive/Classical/index.html.
 F. J. López and F. Martín, "Complete Minimal Surfaces in ," Publicacions Matematiques, 43(2), 1999 pp. 341–449. www.ugr.es/~fmartin/dvi/survey.pdf.