Sudoku Players' Forum (clone)

I have been playing sudoku for a few months. Have found a few techniques including pencil marking. However cannot get the next step on this puzzle.
Can someone please explain how to get another number here.
Thanks
Thomas

since there is already a 45 in column 4 rows 1 and 3 of column 4 must contain 67
that means row 6 of column 4 can only be a 1
this leaves only singles left to solve the puzzle.

Thanks Arkie