TY  JOUR
TI  Ellipse: tangent and normal
KW  descriptive geometry
KW  academic competition
KW  tangent
KW  normal
KW  ellipse
KW  ellipse focus.
JO  Geometry & Graphics
AU  Sal'kov, N.A.
PY  2013
IS  1
PB  INFRA-M Academic Publishing LLC.