Non-orientable surfaces in 4-dimensional space
  This article is a survey article that gives detailed constructions and illustrations of some of the standard examples of non-orientable surfaces that are embedded and immersed in 4-dimensional space. The illustrations depend upon their 3-dimensional projections, and indeed the illustrations here depend upon a further projection into the plane of the page. The concepts used to develop the illustrations will be developed herein. 
Yongju Bae (Kyungpook National University), J. Scott Carter (Univ. of   South Alabama), Seonmi Choi (Kyungpook National Univ...
math.GT