There are two ambigrams which is designed by John Langdon. This two words appeared in the book which named angels and demons which author was Dan Brown. This typographer, John Longdin, was very famous in this field (ambigrams). Even Dan Brown used Longdan’s name as main role’s name- Rober Longdan who is a very famous protagonist. Because of his design, I did 5 ambigrams for my portfolio. Langdon is now a professor of typography and corporate identity at Drexel University in Philadelphia. He continues to do work on ambigrams, as well and fine art works that incorporate language, type, and philosophy. He also had a online store which used to sell his design by iPhone case or shirt.
Langdon was also influenced greatly by the Taoist graphic symbol yin/yang, and the graphic work of M.C. Escher — both black and white representations of concepts that encourage viewing things from more than a single point of view. Unhappy with marginal success at designing words that would tessellate a plane like Escher’s birds and fish, Langdon’s discovery of the NEW MAN and VISTA logos (by Raymond Loewy and Dick Hess, respectively), which featured rotational symmetry, steered him in the direction of what later became known as ambigrams. The blend of his Taoist philosophy with ambigrams resulted in the 1992 publication of his book Wordplay.