Canada express entry: Reference letter

I have collected my employment reference letters from previous employers. It states my date of joining and all other roles and responsibilities but the hours of work and salary is not mentioned. I do have my salary slips and offer letters from these companies. So, are these supporting documents enough or is it mandatory to have it in the reference letter?? Please help.

Please advise what stage of the express entry you are at? Have you already submitted an entry and been nominated to apply?