# How to plot an implicit equation with separate dispersion lines of Lamb waves

I'd like to plot (to try reproduce) dispersion curves of Lamb waves as in http://en.wikipedia.org/wiki/Lamb_waves
But I can't to separate each lines. I was reduce the dispersion equations as X=ωd/Vs, Y=V/Vs, here Vs/Vl=S=0.5;d=0.001;

ContourPlot[Cot[1/2 Sqrt[X^2 (1-1/Y^2)]] Tan[1/2Sqrt[X^2(S^2-1/Y^2)]] ==
((d^2 (-2 + Y^2))/( 2 Sqrt[X^2 (S^2 - 1/Y^2)] Sqrt[X^2 (1 - 1/Y^2)]))


Thanks for all. Please, help me to separate lines.

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Welcome to Mathematica.SE! Please format your post for readability when asking question. I formatted it for you now, you can see how by clicking the edit link. Also, do show (briefly) what you have tried on your own when asking questions, to clearly illustrate the difficulty you were having. As far as I can tell, you are asking how to plot an implicit equation. Make your question short, and to the point. It is completely unnecessary to post a long equation for that question, as that'll just reduce the likelihood that people'll answer. –  Szabolcs Feb 13 at 20:58
Use ContourPlot to plot implicitly given curves. –  Szabolcs Feb 13 at 20:59
The use of Subscript in variables is discouraged, as you will likely run into problems on evaluation of your code. –  shrx Feb 13 at 21:33