AILSA ALLABY and MICHAEL ALLABY "SEM ." A Dictionary of Earth Sciences. . Encyclopedia.com. (November 15, 2024). https://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/sem

AILSA ALLABY and MICHAEL ALLABY "SEM ." A Dictionary of Earth Sciences. . Retrieved November 15, 2024 from Encyclopedia.com: https://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/sem

FRAN ALEXANDER , PETER BLAIR , JOHN DAINTITH , ALICE GRANDISON , VALERIE ILLINGWORTH , ELIZABETH MARTIN , ANNE STIBBS , JUDY PEARSALL , and SARA TULLOCH "sem. ." The Oxford Dictionary of Abbreviations. . Encyclopedia.com. (November 15, 2024). https://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/sem-0

FRAN ALEXANDER , PETER BLAIR , JOHN DAINTITH , ALICE GRANDISON , VALERIE ILLINGWORTH , ELIZABETH MARTIN , ANNE STIBBS , JUDY PEARSALL , and SARA TULLOCH "sem. ." The Oxford Dictionary of Abbreviations. . Retrieved November 15, 2024 from Encyclopedia.com: https://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/sem-0