I am grateful to the following persons (listed alphabetically) for various help in conducting this research (data sharing, field trips arranging, providing literature sources, giving access to collections, ID suggestions, etc.):
| Martin Albrecht (Bern, Switzerland) | Zdravko Kolev (Helsinki, Finland) | Vladimir Savchuk (Feodosiya, Ukraine) |
| Artur Choch (Kiev, Ukraine) | Stanislav Korb (Nizhny Novgorod, Russia) | Elena Skobtsova (Orel, Russia) |
| Rienk de Jong (Leiden, the Netherlands) | Aleksandr Kovalchuk (Kharkov, Ukraine) | Aleksandr Slutsky (Kharkov, Ukraine) |
| Sergey Demyanenko (Severodonetsk, Ukraine) | Dmitry Kovalchuk (Kharkov, Ukraine) | Konstantin Slutsky (Kharkov, Ukraine; Urbana, IL, USA) |
| Aleksandr Drogvalenko (Kharkov, Ukraine) | Gennadiy Kuznetsov (Volgograd, Russia) | Boris Stradomsky (Rostov-on-Don, Russia) |
| Kirill Goloborod'ko (Dnepropetrovsk, Ukraine) | Boris Loboda (Kharkov, Ukraine) | Sergey Trotsenko (Cherkassy, Ukraine) |
| Viktor Gramma (Kharkov, Ukraine) | Dmitry Morgun (Moscow, Russia) | Pavel Voloshin (Kharkov, Ukraine) |
| Julia Guglya (Kharkov, Ukraine) | Igor Pljushtch (Kiev, Ukraine) | Wolfgang Wagner (Ulm, Germany) |
| Natalia Kaigorodova (Feodosiya, Ukraine) |
