25 Edmonds, T., C. Edmonds, B. Tsay, Fundamental Managerial Accounting Concepts, Mc Grow – Hill, 2000, р.533
26 Трифонова, К., Финанси на фирмата, С., 2012 г., с. 159
27 https://www.strom21.eu/
28 Alexander W. Bartik, Marianne Bertrand, Zoe Cullen, Edward L. Glaeser, Michael Luca, and Christopher Stanton, The impact of COVID-19 on small business outcomes and expectations, PNAS Harvard Business School, July 28, 2020 https://doi.org/10.1073/pnas.2006991117
29 Alexander W. Bartik, Marianne Bertrand, Zoe Cullen, Edward L. Glaeser, Michael Luca, and Christopher Stanton, The impact of COVID-19 on small business outcomes and expectations, PNAS, Harvard Business School, July 28, 2020 https://doi.org/10.1073/pnas.2006991117
30 Alexander W. Bartik, Marianne Bertrand, Zoe Cullen, Edward L. Glaeser, Michael Luca, and Christopher Stanton, The impact of COVID-19 on small business outcomes and expectations, PNAS, Harvard Business School, July 28, 2020 https://doi.org/10.1073/pnas.2006991117