Triangulation is important to improve the credibility of research . There are different types of triangualtion including theoretical,methodological, data. You can collect more than two sources of data(primary and secondary) to improve credibility.

Refer for more information

https://edisciplinas.usp.br/pluginfile.php/4031534/mod_resource/content/1/triangulação%20metodologica.pdf

Many thanks Dr. Hiranya.

The following paper deals with the issue; you may want to check it out.

Intensive triangulation of qualitative research and quantitative data to improve recruitment to randomized trials: the quintet approach

L Rooshenas, S Paramasivan… - … Health Research, 2019 - journals.sagepub.com

Thanks much Dr. Ahmed.