Are these typos?

[Shentao YANG]

http://www.math.toronto.edu/courses/apm346h1/20169/PDE-textbook/Chapter9/S9.1.html#mjx-eqn-eq-9.1.15
I think the coefficient for last term should be ${1 \over {2\pi c}}$ instead of ${1 \over {4\pi c}}$.

http://www.math.toronto.edu/courses/apm346h1/20169/PDE-textbook/Chapter9/S9.1.html#mjx-eqn-eq-9.1.19
I think this equation should be $(\Delta  + {{{\omega ^2}} \over {{c^2}}})v = {1 \over {{c^2}}}f(x)$ instead of  $(\Delta  + {{{\omega ^2}} \over {{c^2}}})v = f(x)$

[Victor Ivrii]

1) Yes, it is typo. Corrected

2) No, since the wave equation is in the form
$$
\Delta u - c^{-2}u_{tt}= fe^{i\omega t}.
$$