The regulation problem is addressed for single-input, single-output, linear unknown stable systems P(s), of unknown order, with exosystems generating biased multi-sinusoidal references and/or disturbances containing at most q known frequencies omega(i), 1 <= i <= q. Sufficient conditions are presented which require the knowledge of sign [P(0)] and either sign{Re[P(j omega(i))]} or sign{Im[P(j omega(i))]}, 1 <= i <= q. The constructive proofs lead to the design of regulators with minimal order (2q + 1), provided that the gains are sufficiently small. For stable plants P(s) such that Re[P(j omega)] > 0, for any omega is an element of R, a universal modular regulator is designed without gain limitations.