  I discuss methods of calculation of propagator diagrams (massless, those of
Heavy Quark Effective Theory, and massive on-shell diagrams) up to 3 loops.
Integration-by-parts recurrence relations are used to reduce them to linear
combinations of basis integrals. Non-trivial basis integrals have to be
calculated by some other method, e.g., using Gegenbauer polynomial technique.
Many of them are expressed via hypergeometric functions; in the massless and
HQET cases, their indices tend to integers at $\epsilon\to0$. I discuss the
algorithm of their expansion in $\epsilon$, in terms of multiple $\zeta$
values. These lectures were given at Calc-03 school, Dubna, 14--20 June 2003.
