Sentences:type of journal

Hi teachers,

Please somebody correct my sentences?

The authors claimed that they had selected the medical journals on the basis of their wide readership by general practitioners and cardiologists. There is no proof for this claim. This suggests for the need of further research (or this suggests of the need for further research?) into the methodology of selecting journal for this type of study. Researchers can select the combination of journals with high impact factors and consider important and popular to doctors. The information of the list of important and popular journals can be gained by doing a pilot study to doctors and asked them to rank the journals they considered important and popular to them.
Thanks,
dean

This suggests for the need of further research (or this suggests of the need for further research?)- this suggests the need for further research
selecting journal- journals
consider important- considered