N. Eilersen was a furniture maker and grundlagt means "established" in Danish.
The other sticker is a sign that Eilersen was a member of the Danish furnituremakers control, an organization whose aim was to guaranty the quality and origin of the furniture.
The logo you are describing is N. Eilersen's and it was indeed a member of the DFMC. The fact that you have a DFMC sticker means that the chair cannot be older than 1959 (the year the organization was founded).
Concerning the authenticity of the chair... difficult to say without a picture. However, N. Eilersen is not exactly one of the most famous Danish furniture maker of the period so it would be quite surprising that someone bothered to make fakes.
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