Matrix / vectors notation
Different fields use different conventions. For instance, mathematicians frequently use lower case italic letters for vectors and upper case italic letters for matrices.

For physics and chemistry, IUPAP and IUPAC recommend (some journal guidelines are in agreement with this recommendation) a number of symbols for quantities that can be found in the following document:

E R Cohen et al., "Quantities, Units and Symbols in Physical Chemistry", IUPAC Green Book, 3rd Edition, 2nd Printing, IUPAC &amp; RSC Publishing, Cambridge, 2008

In particular, the document recommends to typeset matrices and vectors with a bold italic font.