Support inbook and incollection

[Firgrep]

Currently unable to support things like

@incollection{koch2018sein,
  author    = {Koch, A. F.},
  title     = {Das Sein. Erster Abschnitt. Die Qualität},
  editor    = {Quante M. and Mooren N.},
  booktitle = {Georg Wilhelm Friedrich Hegel, Wissenschaft der Logik. Band 1: Die objektive Logik}, // **Add the book's main title here**
  publisher = {Felix Meiner Verlag},
  address   = {Hamburg},
  isbn      = {978–3-7873–3186-4},
  year      = {2018},
  pages     = {43-144}
}