• The electronic structure of the nitrogen molecule has been the subject ( or theme ) of much investigation .
• The shapes of such curves have long been subjects for study .
• The electronic structure of the nitrogen molecule has been the subject ( or theme ) of much investigation .
• The shapes of such curves have long been subjects for study .
Циммерман М., Веденеева К.. Русско-Английский научно-технический словарь переводчика. Russian-English scientific dictionary for translators. 2012