[1] W. Boy: U¨ber die Curvatura integra und die Topologie geschlossener Flchen, Math. Ann. 57 (1903) 151-184.

[2] C. Giller: Towards a classical knot theory for surfaces in R4 Illinois. J. Math. 26 (1982) 591-631.

[3] J. W. Milnor and J. D. Stasheff: Characteristic classes. Annals of Mathematics Studies, No. 76. Princeton University Press 1974.

[4] E. Ogasa: The projections of n-knots which are not the projection of any unknotted knot Journal of knot theory and its ramifications, 10 (2001) 121-132 UTMS 97-34, math.GT/0003088

[5] E. Ogasa: Singularities of projections of n-dimensional knots Mathematical Proceedings of Cambridge Philosophical Society 126 (1999) 511-519 UTMS96-39

[6] E. Ogasa: Ijigen e no tobira (In Japanese) Nippon Hyoron Sha Co., Ltd. 2009 Eiji Ogasa Computer Science, Meijigakuin University, Yokohama, Kanagawa, 244-8539, Japan ogasa@mail1.meijigkakuin.ac.jp pqr100pqr100@yahoo.co.jp http://www.geocities.jp/n dimension n dimension/list.html (Don't forget the three in this address. You can find this website by typing in the author's name 'Eiji Ogasa' in the search engine.)