LaTeX.org

The attachment is a scan from the book "Arithmetic Geometry", edited by Cornell & Silverman. When I first got this book, I was immediately fascinated at the font. This is by far the best font I ever saw in a math book. I went thru every font in Hartke's article A Survey of Free Math Fonts , but ...

I want to use a circled perpendicular sign to denote the orthogonal direct sum. It looks like \oplus except the bottom part of "+" is missing. This symbol is available in mathabx package as \obot. But I don't want to use this package since it changes the math font, and is incompatible with fourier ...