replace in opening quotations

node98.html

@@ -100,7 +100,7 @@ stretched wavetable lookup.</CAPTION>
 <TABLE>
 <CAPTION ALIGN="BOTTOM"><STRONG>Figure 6.14:</STRONG>
 Intermediate audio signals from Figure <A HREF="#fig06.12">6.13</A>: (a) the
-result of multiplying the phasor by the ``index"; (b) the same, clipped to 
+result of multiplying the phasor by the "index"; (b) the same, clipped to 
 lie between -0.5 and 0.5; (c) the output.</CAPTION>
 <TR><TD><IMG
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