From 1922 to 1937 Engel published Lie 's collected works in six volumes and prepared a seventh (which in fact was not published until 1960).
Mula 1922-1937-publish Engel humiga / magsinungaling 's nakolekta na gumagana sa anim na volume na at handa ng ikapitong (na sa katunayan ay hindi nai-publish na hanggang 1960).