Triangulation

Triangulation strengthens the credibility of qualitative findings by examining a phenomenon from more than one vantage point. If several independent sources or methods converge on the same conclusion, that conclusion is far harder to attribute to the bias of any one of them.

Denzin's four types are the standard reference: data triangulation (different sources, times or settings), investigator triangulation (multiple researchers coding independently), theory triangulation (interpreting findings through more than one theoretical lens) and methodological triangulation (combining methods such as interviews with document analysis or survey data).

Divergence between sources is a finding, not a failure — contradictions often reveal something important about context or perspective, and should be reported and explained rather than smoothed over. Describe in your methodology exactly which type you used and how the sources were compared, since a vague claim to have triangulated carries little weight.