Direct frequency estimation based adaptive algorithm for a second-order adaptive FIR notch filter. - R. Punchalard; A. Lorsawatsiri; W. Loetwassana; Jeerasuda Koseeyaporn; Paramote Wardkein; A. Roeksabutr (Signal Process., 2008)

Unbiased plain gradient algorithm for a second-order adaptive IIR notch filter with constrained poles and zeros. - W. Loetwassana; R. Punchalard; Jeerasuda Koseeyaporn; Paramote Wardkein (Signal Process., 2010)