Answer
$\sinh^{-1}(\dfrac{\ln y}{\sqrt 3})+C$
Work Step by Step
Use the formula: $\int\dfrac{dx}{\sqrt{a^2+x^2}}=\sinh^{-1}\dfrac{x}{a}+C $.
Let $I=\int\dfrac{dy}{y\sqrt{3+(\ln y)^2}} $
Suppose $u=\ln y \implies du=\dfrac{dy}{y}$
Therefore, $I=\int\dfrac{du}{\sqrt{3+u^2}}=\sinh^{-1} (\dfrac{\ln y}{\sqrt{3}})+C$