How to add multiple font files for the same font?

I'm looking at the MDC page for the @font-face CSS rule, but I don't get one thing. I have separate files for bold, italic and bold + italic. How can I embed all three files in one @font-face rule? For example, if I have:

@font-face {
    font-family: "DejaVu Sans";
    src: url("./fonts/DejaVuSans.ttf") format("ttf");
}
strong {
    font-family: "DejaVu Sans";
    font-weight: bold;
}

The browser will not know which font to be used for bold (because that file is DejaVuSansBold.ttf), so it will default to something I probably don't want. How can I tell the browser all the different variants I have for a certain font?

The solution seems to be to add multiple @font-face rules, for example:

@font-face {
    font-family: "DejaVu Sans";
    src: url("fonts/DejaVuSans.ttf");
}
@font-face {
    font-family: "DejaVu Sans";
    src: url("fonts/DejaVuSans-Bold.ttf");
    font-weight: bold;
}
@font-face {
    font-family: "DejaVu Sans";
    src: url("fonts/DejaVuSans-Oblique.ttf");
    font-style: italic, oblique;
}
@font-face {
    font-family: "DejaVu Sans";
    src: url("fonts/DejaVuSans-BoldOblique.ttf");
    font-weight: bold;
    font-style: italic, oblique;
}

By the way, it would seem Google Chrome doesn't know about the format("ttf") argument, so you might want to skip that.

(This answer was correct for the CSS 2 specification. CSS3 only allows for one font-style rather than a comma-separated list.)