In 1913 Thesing joined Otto val Halem as partner and managing director of Veit and Comp. Following wartime propaganda collaboration with a German-Austrian publishers' association, Veit & Comp. was incorporated into Walter de Gruyter on 1 January 1919 – despite some political reservations from Thesing, who was on the political left. In May 1920 he withdrew as a partner from the firm for health reasons.
Lectures on Biology. London : John Bale, Sons & Danielsson, 1910. Translated from the 2nd ed. by W. R. Boelter.
Stammesgeschichte der Liebe, Berlin : Brehm, . Translated by Eden and Cedar Paul as Genealogy of love, London : Routledge, 1933. American edition Genealogy of sex: sex in its myriad forms, from the one-celled animal to the human being. New York : Emerson Books, 1934.
Schule der Biologie , 1934. Translated by Eden and Cedar Paul as School of Biology, London: G. Routledge and sons, Ltd., 1935.
(tr. with Marguerite Thesing) Mein Leben und Work by Henry Ford. Leipzig: Paul List Verlag, 1923. Translated from My Life and Work, New York: Doubleday, Page & Co., 1923
(tr.) Hauptmann Sorrell und sein Sohn: roman by Warwick Deeping. Bremen: Schünemann, 1927. Translated from Sorrell and Son, London: Cassell & Co.
(tr.) Der rote Handel droht! : Der Frotschritt des Fünfjahresplans der Sowjets by H. R. Knickerbocker. 1931. Translated from Fighting the Red trade menace
(tr.) Bezwinger des Hungers by Paul Henry de Kruif. Berlin: Holle & Co. Verlag,  . Translated from Hunger fighters.
(tr.) Frau Buck and ihre Töchter. Roman by Warwick Deeping. Bremen: Carl Schünemann, Verlag, . Translated from The Road.