Convert from stremma to cover

Unit Definition (stremma)
The stremma is a traditional Greek unit of area, now redefined to equal exactly 1000 square meters or 0.1 hectare (0.24710 acre).

Unit Definition (cover)
The Cover is a traditional Welsh unit of area, standardized in the British system to be exactly 2/3 acre (about 0.2698 hectare). The word is an Anglicized version of the Welsh name cyfair for the unit.