Add punctuation: From this time until his retirement in 1919 he held the chair of physics at Lund
A: From this time until his retirement in 1919 he held the chair of physics at Lund.

Add punctuation: After 1971 Novikov became interested in mathematical physics and dynamical systems
A: After 1971 Novikov became interested in mathematical physics and dynamical systems .

Add punctuation: It as soon as the idea of toys no sale is required products just fly off the shelves all by themselves
A:
It as soon as the idea of toys , no sale is required ; products just fly off the shelves all by themselves .