Notation

$x$	...	Scalar
$\vec{x}$	...	Vector
$\vec{e}_x$	...	Unity vector in direction x
$\vec{e}_n$	...	Unity vector in direction of vector $\vec{n}$
$\vec{x} \cdot \vec{y}$	...	Scalar (in) product
$\vec{x} \times \vec{y}$	...	Cross product
$\frac{\partial (\cdot)}{\partial t}$	...	Partial derivative with respect to $t$
$\ensuremath{{\mathbf{\nabla}}}$	...	Nabla operator
$\ensuremath{{\mathbf{\nabla}}}\vec{x}$	...	Gradient of $\vec{x}$
$\ensuremath{{\mathbf{\nabla}}}\cdot \vec{x}$	...	Divergence of $\vec{x}$
$\ensuremath{{\mathbf{\nabla}}}\cdot \ensuremath{{\mathbf{\nabla}}}= \ensuremath{{\mathbf{\nabla}}}^2$	...	LAPLACE operator
$\langle\cdot\rangle$	...	Statistical average
$f(\vec{r},\vec{k},t)$	...	Distribution function
$\mathcal{F} , \mathcal{F}^{-1}$	...	FOURIER transform and inverse FOURIER transform respectively
$J_n(\cdot)$	...	BESSEL function of nth order