Linear widths of Holder-Nikol'skii classes of periodic functions of several variables

We consider the linear widths lambda(N)(W-p(r)(T-n), L(q)) and lambda(N) (H-p(r)(T-n), L(q)) of the classes W-p(r)(T-n) and H-p(r)(T-n) of periodic functions of one or several variables in the space L(q). For the Sobolev classes W-p(r)(T-n) of functions of one or several variables, we state some well-known results without proof; for the Holder-Nikol'skii classes H-p(r)(T-n), we state some well-known results, prove some new results, and present some previously unpublished proofs.