Παραπομπή σε μορφή APA (7η εκδ.)
Birkett, D. (2021). Safety essentials for business and leisure travel: Air, land, sea and during pandemics! Cambridge Scholars Publishing.
Παραπομπή σε μορφή Chicago (17η εκδ.)
Birkett, David. Safety Essentials for Business and Leisure Travel: Air, Land, Sea and During Pandemics! Newcastle upon Tyne, England: Cambridge Scholars Publishing, 2021.
Παραπομπή σε μορφή MLA (9th εκδ.)
Birkett, David. Safety Essentials for Business and Leisure Travel: Air, Land, Sea and During Pandemics! Cambridge Scholars Publishing, 2021.
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