# Bulk modulus of Liquid helium and first sound

Does anyone know where to find the bulk modulus of liquid helium ?

I've been looking all over the internet but everywhere I get N/A. Any tips ?

I'd need it to estimate the speed of first sound in liquid helium which is given by:

$c_1=\sqrt{\left.\frac{\partial p}{\partial\rho}\right|_\sigma}$

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