Low-cost XRF spectrometer for agricultural sample analysis: assembly details and soil fertility prediction performance - Tavares, Tiago Rodrigues; Santos, Felipe Rodrigues dos; Silva, Thainara Rebelo da; Rezende, Vinicius Pires; Almeida, Eduardo de; Oldoni, Henrique; Amaral, Lucas Rios do; Carvalho, Hudson Wallace Pereira de (Scientia Agricola, 2025)